Patent Publication Number: US-10762436-B2

Title: Systems and methods for recommending pages

Description:
FIELD OF THE INVENTION 
     The present technology relates to the field of content provision. More particularly, the present technology relates to techniques for recommending pages. 
     BACKGROUND 
     Today, people often utilize computing devices (or systems) for a wide variety of purposes. Users can use their computing devices to, for example, interact with one another, access content, share content, and create content. In some cases, content items can include postings from members of a social network. The postings may include text and media content items, such as images, videos, and audio. The postings may be published to the social network for consumption by others. 
     Under conventional approaches, a user may navigate to or be presented with various content items in a social network. The content items can come from pages associated with members of the social network. In some instances, the content items may be of high interest to the user. If the user expresses interest in a particular content item, the social network may attempt, based on the content item, to provide to the user additional content items that would also be of interest to the user. Providing such additional content items can enhance the user experience and may help realize the full potential of the social network. Unfortunately, attempts to provide such additional content items and to maintain a high level of interest from the user often fail. The growing size of social networks can also pose problems with respect to the goal of providing content items of high interest to the user. As available content grows in amount, in theory, the likelihood of finding more content items of high interest to the user should increase. However, in practice, the ability to identify content items of high interest to the user can be complicated by the sheer volume of content. 
     SUMMARY 
     Various embodiments of the present disclosure can include systems, methods, and non-transitory computer readable media configured to determine a respective embedding for each entity in a set of entities that are accessible through the social networking system, wherein each embedding is learned based at least in part on one or more sessions of connections formed between users and entities of the social networking system, and wherein an embedding for an entity is a numerical representation of the entity. One or more candidate entities that are related to a first entity can be determined based at least in part on the respective embeddings for the candidate entities and the first entity. At least a first candidate entity from the one or more candidate entities can be provided as a recommendation to a user that formed a connection with the first entity. 
     In an embodiment, the systems, methods, and non-transitory computer readable media are configured to obtain data describing a sequence of connections formed between users and entities of the social networking system, the data including a respective timestamp at which each connection was formed, determine a set of sessions from the sequence, wherein each session includes a threshold number of entities with which a connection was formed, train at least one model using a skip-gram negative down sampling technique based at least in part on the set of sessions, and map each entity in the set of entities to a respective embedding based at least in part on the at least one model. 
     In an embodiment, the systems, methods, and non-transitory computer readable media are configured to determine each session based at least in part on a predefined time interval. 
     In an embodiment, the systems, methods, and non-transitory computer readable media are configured to determine a period of inactivity between a first set of connections and a second set of connections in the sequence, the period of inactivity having a threshold length of time, determine that the first set of connections correspond to a first session, and determine that the second set of connections correspond to a second session. 
     In an embodiment, the systems, methods, and non-transitory computer readable media are configured to generate one or more clusters of entities, wherein the entities are clustered based at least in part on their respective embeddings and identify the one or more candidate entities from the clusters, wherein a respective distance measurement between a candidate entity and the first entity satisfies a threshold distance. 
     In an embodiment, the distance is measured based on a cosine similarity between the embedding for the candidate entity and the embedding for the first entity. 
     In an embodiment, the systems, methods, and non-transitory computer readable media are configured to determine that a predicted conversion rate for the user and the first candidate entity satisfies a threshold conversion rate. 
     In an embodiment, the systems, methods, and non-transitory computer readable media are configured to determine a machine learning model that is trained to predict the conversion rate, wherein the model is trained based at least in part on entity connections that were previously formed by the user. 
     In an embodiment, the predicted conversion rate measures a likelihood that the user will form a connection with the first candidate entity. 
     In an embodiment, an entity corresponds to at least a page, user profile, group, story, or status update that is accessible through the social networking system. 
     It should be appreciated that many other features, applications, embodiments, and/or variations of the disclosed technology will be apparent from the accompanying drawings and from the following detailed description. Additional and/or alternative implementations of the structures, systems, non-transitory computer readable media, and methods described herein can be employed without departing from the principles of the disclosed technology. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  illustrates an example system including an example entity module, according to an embodiment of the present disclosure. 
         FIG. 2  illustrates an example of an embedding module configured to generate embeddings of sequences of user interactions with entities, according to an embodiment of the present disclosure. 
         FIG. 3  illustrates an example of an entity recommender module configured to provide entity recommendations, according to an embodiment of the present disclosure. 
         FIG. 4  illustrates an example process for determining page recommendations, according to an embodiment of the present disclosure. 
         FIG. 5  illustrates an example process for determining entity embeddings, according to an embodiment of the present disclosure. 
         FIG. 6  illustrates a network diagram of an example system including an example social networking system that can be utilized in various scenarios, according to an embodiment of the present disclosure. 
         FIG. 7  illustrates an example of a computer system or computing device that can be utilized in various scenarios, according to an embodiment of the present disclosure. 
     
    
    
     The figures depict various embodiments of the disclosed technology for purposes of illustration only, wherein the figures use like reference numerals to identify like elements. One skilled in the art will readily recognize from the following discussion that alternative embodiments of the structures and methods illustrated in the figures can be employed without departing from the principles of the disclosed technology described herein. 
     DETAILED DESCRIPTION 
     Approaches for Recommending Pages 
     Today, people often utilize computing devices (or systems) for a wide variety of purposes. Users can use their computing devices to, for example, interact with one another, access content, share content, and create content. In some cases, content items can include postings from members of a social network. The postings may include text and media content items, such as images, videos, and audio. The postings may be published to the social network for consumption by others. 
     Under conventional approaches, a user may navigate to or be presented with various content items in a social network. The content items can come from pages associated with members of the social network. In some instances, the content items may be of high interest to the user. If the user expresses interest in a particular content item, the social network may attempt, based on the content item, to provide to the user additional content items that would also be of interest to the user. Providing such additional content items can enhance the user experience and may help realize the full potential of the social network. Unfortunately, attempts to provide such additional content items and to maintain a high level of interest from the user often fail. The growing size of social networks can also pose problems with respect to the goal of providing content items of high interest to the user. As available content grows in amount, in theory, the likelihood of finding more content items of high interest to the user should increase. However, in practice, the ability to identify content items of high interest to the user can be complicated by the sheer volume of content. Accordingly, such conventional approaches may not be effective in addressing these and other problems arising in computer technology. 
     An improved approach rooted in computer technology overcomes the foregoing and other disadvantages associated with conventional approaches specifically arising in the realm of computer technology. In various embodiments, entity recommendations can be generated for users in a social networking system based on sequences of user connections with entities. Such entities can include pages, user profiles, groups, stories, cities, and status updates, to name some examples. A user can interact with an entity in various ways and such interactions can result in the user forming a connection with the entity. For example, an entity may be a page that is accessible through the social networking system. The page may correspond to some type of subject matter (e.g., a business, topic, location, user, etc.). Users of the social networking system can navigate to the page to learn more about the subject matter as well as access and/or post content through the page. Users have the option to be associated with the page, for example, by “liking” the page (e.g., selecting a “like” option through the social networking system) or by becoming a “fan” the page (e.g., selecting a “fanning” option through the social networking system). In this example, a user can form a connection with the page by perform actions such as visiting the page, fanning the page, and/or posting through the page, for example. Other types of interactions through which entity connections can be formed include accessing (or visiting) a user profile, posting to a user profile, friending a user, joining a group, associating with cities, reading stories (e.g., stories presented in a user&#39;s news feed), and/or liking a status update. Naturally, this list of interactions is not exhaustive and, depending on the implementation, there may be many other types of interactions through which connections between users and entities may be formed. 
     In various embodiments, entity recommendations can be determined from embeddings that are generated using a skip-gram negative down sampling technique. In general, a learning algorithm (e.g., a two-layer neural net) can be used to generate corresponding embeddings (or vectors) for words in sentences. Such embeddings are typically used for natural language processing. In one example, respective embeddings for a sequence of words in a sentence can be learned. Each word embedding can be represented using a vector that has a semantic structure. Such embeddings can be used to determine a word&#39;s relation to other words, for example, using vector operations. In various embodiments, a skip-gram negative down sampling technique can be used to generate embeddings that correspond to sequences of user interactions with entities in the social networking system. Thus, each user can be treated as a sentence and every entity with which the user has formed a connection can be treated as a word. The resulting embeddings have semantic meaning. That is, a distance between an embedding for a first entity and an embedding for a second entity represents a probability that a user will connect with both the first entity and the second entity within the same time frame or sequence (e.g., session). In some embodiments, the respective distances between such embeddings can be used to cluster entities that are closely related to one another. In general, entities determined to be closely related tend to have the highest probability of appearing within the same time frame or sequence. As a result, entities that are related to one another can easily be identified. Moreover, entities to be recommended to users can also easily be identified. In various embodiments, an embedding is a numerical representation of an entity, for example, using a vector. 
       FIG. 1  illustrates an example system  100  including an example entity module  102 , according to an embodiment of the present disclosure. As shown in the example of  FIG. 1 , the entity module  102  can include an embedding module  104  and an entity recommender module  106 . In some instances, the example system  100  can include at least one data store  108 . The components (e.g., modules, elements, etc.) shown in this figure and all figures herein are exemplary only, and other implementations may include additional, fewer, integrated, or different components. Some components may not be shown so as not to obscure relevant details. 
     In some embodiments, the entity module  102  can be implemented, in part or in whole, as software, hardware, or any combination thereof. In general, a module as discussed herein can be associated with software, hardware, or any combination thereof. In some implementations, one or more functions, tasks, and/or operations of modules can be carried out or performed by software routines, software processes, hardware, and/or any combination thereof. In some cases, the entity module  102  can be implemented, in part or in whole, as software running on one or more computing devices or systems, such as on a user or client computing device. In one example, the entity module  102 , or at least a portion thereof, can be implemented as or within an application (e.g., app), a program, or an applet, etc., running on a user computing device or a client computing system, such as the user device  610  of  FIG. 6 . In another example, the entity module  102  or at least a portion thereof can be implemented using one or more computing devices or systems that include one or more servers, such as network servers or cloud servers. In some instances, the entity module  102  can, in part or in whole, be implemented within or configured to operate in conjunction with a social networking system (or service), such as the social networking system  630  of  FIG. 6 . 
     The entity module  102  can be configured to communicate and/or operate with the at least one data store  108 , as shown in the example system  100 . The at least one data store  108  can be configured to store and maintain various types of data including, for example, the respective entity connections made by users in the social networking system as well as the time at which such connections were made. In some implementations, the at least one data store  108  can store information associated with the social networking system (e.g., the social networking system  630  of  FIG. 6 ). The information associated with the social networking system can include data about users, social connections, social interactions, locations, geo-fenced areas, maps, places, events, pages, groups, posts, communications, content, feeds, account settings, privacy settings, a social graph, and various other types of data. In some implementations, the at least one data store  108  can store information associated with users, such as user identifiers, user information, profile information, user specified settings, content produced or posted by users, and various other types of user data. 
     In various embodiments, the embedding module  104  can be configured to generate embeddings for sequences of user interactions with entities. More details regarding the embedding module  104  will be provided below with reference to  FIG. 2 . The entity recommender module  106  can be configured to provide entity recommendations for users. More details regarding the entity recommender module  106  will be provided below with reference to  FIG. 3 . 
       FIG. 2  illustrates an example of an embedding module  202  configured to generate embeddings of sequences of user interactions with entities, according to an embodiment of the present disclosure. In some embodiments, the embedding module  104  of  FIG. 1  can be implemented as the embedding module  202 . As shown in  FIG. 2 , the embedding module  202  can include a data preparation module  204 , a training data module  206 , and a training module  208 . 
     As mentioned, users can interact with entities and such interactions can form connections between users and the corresponding entities. A connection between a user and an entity can form, for example, when the user perform actions, as described above. In various embodiments, the data preparation module  204  is configured to log each connection that is formed between a user and an entity as well as the time (e.g., timestamp) at which the connection was formed. The data preparation module  204  can aggregate this connection data into a respective user connections model m(P) for each user. The user connections model m(P) represents a sequence of connections made by the user over a period of time. One example representation of a user connections model m(P) is as follows:
 
 m ( P )={{ i   1   ,t   1   },{i   2   ,t   2   }, . . . ,{i   n   ,t   n }},
 
     where P corresponds to a user, i corresponds to an entity, and where t corresponds to a time at which the user formed a connection with the entity i. In some embodiments, the entities included in the user connections model m(P) are all of the same type (e.g., pages, or user profiles, or status updates). In some embodiments, the entities included in the user connections model m(P) are of mixed types (e.g., pages, user profiles, and status updates). 
     The training data module  206  is configured to sessionize the respective user connections model for each user. In other words, the training data module  206  is configured to divide a user connections model into one or more sessions to produce a number of training examples. A session generally refers to a period of time over which a user formed connections with entities. In one example, a session may be defined as the period of time between the time a user logged on to the social networking system and the time the user logged off of the social networking system. In general, sessionization of a user connections model consists of decomposing a sentence (e.g., sequence of a user&#39;s entity connections) into smaller sentences (e.g., sessions) while maintaining the relative order of the connections. In some embodiments, the boundaries of these smaller sentences can be based on time. For example, the training data module  206  can divide the user connections model into sessions that each measure some period of time (e.g., hour, day, week, etc.). In some embodiments, the sessionization can be based on contiguous runs of user activity that are separated by long periods of inactivity. In such embodiments, a boundary between a first session and a second session is defined by a period of inactivity between the first session and the second session that exceeds a median time between sessions. Thus, for example, if m(P) has activity times T s =t 1 , t 2 , t 3 , . . . , t n , the median time between each of the events T s  is calculated (e.g., median(T s )). If the time interval between a first sequence of events and a second sequence of events is greater than the median time (e.g., t j −t i &gt;median(T s )), then the first sequence of events and the second sequence of events are each divided into sub-sequences (or sub-sessions). As a result, this produces sessionized training data that consists of sub-sessions of connection activity. The number of sub-sessions is denoted by subsession(m(P)) in the example below:
 
 m ( P )={ m   {P,1}   ,m   {P,2}   , . . . ,m   {P,subsession(m(P))} }.
 
     After determining the sub-sessions, the training data module  206  can collect and prepare the sub-sessions to be used for training. In some embodiments, the training data module  206  discards any sub-sessions that include only one entity. In some embodiments, the training data module  206  discards any sub-sessions that have an anomalous length (e.g., a length that exceeds some threshold length). 
     In various embodiments, the training module  208  is configured to embed sequence information using a modified skip-gram technique. In such embodiments, the training module  208  can associate each entity i with a vector v i . For example, a training sentence may consist of a sequence of entities i 1 , i 2 , . . . i n . A window of length w (e.g., 3, 4, or 5) can be slid across the training sentence so that each of the entities in the sentence are considered in turn (e.g., i j , i {j+1} , . . . , i {j+w} ). The length of the window parameter is tunable and can vary depending on the implementation. The training module  208  is configured to determine the probability of a pair of entities within the window biased by the amount of time difference between the pair of entities. For example, if a window includes a sequence of page fanning for Page A, Page B, Page C, and Page D, where the time difference between the fanning of Page A and Page B is one hour, the time difference between the fanning of Page B and Page C is 24 hours, and the time difference between the fanning of Page C and Page D is 48 hours, then, when training, the pair (Page A, Page B) can be selected more frequently than the pairs (Page B, Page C) or (Page C, Page D). As a result, the model is trained to correlate the sequence information for entities that occur within a window so that entity connections that are formed closer in time have a higher probability than entity connections that are formed further away in time. 
     In this example, the training module  208  selects an entity k from among the other entities included in the window of length w. For example, the entity k may be selected as follows: 
     
       
         
           
             k 
             = 
             
               
                 i 
                 
                   { 
                   
                     
                       j 
                       + 
                       w 
                     
                     2 
                   
                   } 
                 
               
               . 
             
           
         
       
     
     Next, the training module  208  can select another entity/within the window of length w with a probability that is inversely proportional to the difference in time between the entities. One example approach for determining this probability is as follows: 
     
       
         
           
             
               
                 P 
                 ⁡ 
                 
                   ( 
                   
                     i 
                     l 
                   
                   ) 
                 
               
               = 
               
                 
                   h 
                   
                     Δ 
                     ⁢ 
                     
                         
                     
                     ⁢ 
                     
                       t 
                       ⁡ 
                       
                         ( 
                         
                           l 
                           - 
                           k 
                         
                         ) 
                       
                     
                   
                 
                 
                   
                     ∑ 
                     
                       { 
                       
                         s 
                         ∈ 
                         
                             
                         
                         ⁢ 
                         
                           entities 
                           ⁢ 
                           
                               
                           
                           ⁢ 
                           i 
                           ⁢ 
                           
                               
                           
                           ⁢ 
                           n 
                           ⁢ 
                           
                               
                           
                           ⁢ 
                           window 
                         
                       
                       } 
                     
                   
                   ⁢ 
                   
                     h 
                     
                       Δ 
                       ⁢ 
                       
                           
                       
                       ⁢ 
                       
                         t 
                         ⁡ 
                         
                           ( 
                           
                             s 
                             - 
                             k 
                           
                           ) 
                         
                       
                     
                   
                 
               
             
             , 
           
         
       
     
     where h is a tunable hyper parameter that is less than 1 (e.g., 0.99), where Δt(l−k) represents the difference in time between the connection to entity I and the connection to entity k, and where Δt(s−k) represents the difference in time between the connection to an entity s that is included in the window and the connection to entity k. 
     Next, the training module  208  can perform the learning step, for example, using stochastic gradient descent on the entity pair k and l. In this step, the training module  208  can calculate Pr(v k ,v l ), where v k  is a vector, or embedding, corresponding to the entity k, and where v is a vector, or embedding, corresponding to the entity l. This calculation can be performed by minimizing the following function L: 
     
       
         
           
             L 
             = 
             
               
                 log 
                 ⁡ 
                 
                   ( 
                   
                     Pr 
                     ⁡ 
                     
                       ( 
                       
                         l 
                         , 
                         k 
                       
                       ) 
                     
                   
                   ) 
                 
               
               ⁢ 
               
                 ∼ 
               
               ⁢ 
               
                 
                   log 
                   ( 
                   
                     
                       e 
                       
                         { 
                         
                           
                             v 
                             k 
                           
                           * 
                           
                             v 
                             l 
                           
                         
                         } 
                       
                     
                     
                       
                         ∑ 
                         
                           { 
                           
                             s 
                             ∈ 
                             
                                 
                             
                             ⁢ 
                             entities 
                           
                           } 
                         
                       
                       ⁢ 
                       
                         e 
                         
                           { 
                           
                             
                               v 
                               k 
                             
                             * 
                             
                               v 
                               l 
                             
                           
                           } 
                         
                       
                     
                   
                   ) 
                 
                 . 
               
             
           
         
       
     
     The training module  208  performs a learning step that updates v k  in proportion to the derivative of the function L. The training module  208  performs this approach for every entity that is in every training sentence. In some embodiments, multiple passes over the training data improve the quality of embeddings that are generated. 
       FIG. 3  illustrates an example of an entity recommender module  302  configured to provide entity recommendations, according to an embodiment of the present disclosure. In some embodiments, the entity recommender module  106  of  FIG. 1  can be implemented as the entity recommender module  302 . As shown in  FIG. 3 , the entity recommender module  302  can include a candidate generation module  304  and a recommendation module  306 . 
     Once the embeddings have been collected, the candidate generation module  304  is configured to determine the nearest neighbors for each entity, for example, using the k-nearest neighbors algorithm. In some embodiments, the distance between entities is measured based on the cosine similarity between the respective embeddings of the two entities. Thus, for any given entity i, the number of nearest neighbor entities is determined by a threshold distance Θ i  between the entity i and the neighbor entity. In other words, the list of neighbor entities for entity i includes all entities j for which the respective cosine similarity between the embedding for entity i (v i ) and the embedding for entity j (v j ) is greater than the threshold distance Θ i  (e.g., cos(v i , v j )&gt;Θ i ). In some embodiments, the threshold distance Θ i  can be determined through on-line experimentation. For example, the candidate generation module  304  can collect a number of neighbor entities for a first entity. In some embodiments, some, or all, of these neighbor entities as suggestions to a user when the user makes a connection to the first entity. For each neighbor entity, the candidate generation module  304  can determine a respective conversion rate that measures the rate at which the user forms a connection with the neighbor entity when the neighbor entity is presented as a suggestion. Neighbor entities that have a respective conversion rate that is higher than an average conversion rate of all suggestions can are identified as quality suggestions and, therefore, can be provided as suggestions to users. 
     The recommendation module  306  is configured to generate entity recommendations, or suggestions, to users based on the users&#39; past connections to entities. In various embodiments, the recommendation module  306  can determine candidate entities for every previous connection formed by a user, as described above. The recommendation module  306  can also retrieve features for the candidate entities. The recommendation module  306  can then apply a machine learning (ML) process to predict a conversion rate of a user for a given candidate entity. That is, the recommendation module  306  can train the ML model to predict a likelihood that the user will form a connection with the candidate entity. The recommendation module  306  can rank and provide entity recommendations to a user based on the respective conversion rate that is predicted for each entity. 
       FIG. 4  illustrates an example process  400  for determining page recommendations, according to an embodiment of the present disclosure. It should be appreciated that there can be additional, fewer, or alternative steps performed in similar or alternative orders, or in parallel, within the scope of the various embodiments discussed herein unless otherwise stated. At block  402 , a respective embedding is determined for each entity in a set of entities that are accessible through the social networking system, wherein each embedding is learned based at least in part on one or more sessions of connections formed between users and entities of the social networking system. At block  404 , one or more candidate entities that are related to a first entity can be determined based at least in part on the respective embeddings for the candidate entities and the first entity. At block  406 , at least a first candidate entity from the one or more candidate entities can be provided as a recommendation to a user that formed a connection with the first entity. 
       FIG. 5  illustrates an example process  500  for determining entity embeddings, according to an embodiment of the present disclosure. It should be appreciated that there can be additional, fewer, or alternative steps performed in similar or alternative orders, or in parallel, within the scope of the various embodiments discussed herein unless otherwise stated. At block  502 , data describing a sequence of connections formed between users and entities of the social networking system is obtained, the data including a respective timestamp at which each connection was formed. At block  504 , a set of sessions from the sequence are determined, wherein each session includes a threshold number of entities with which a connection was formed. At block  506 , at least one model is trained using a skip-gram negative down sampling technique based at least in part on the set of sessions. At block  508 , each entity in the set of entities is mapped to a respective embedding based at least in part on the at least one model. 
     It is contemplated that there can be many other uses, applications, and/or variations associated with the various embodiments of the present disclosure. For example, in some cases, user can choose whether or not to opt-in to utilize the disclosed technology. The disclosed technology can also ensure that various privacy settings and preferences are maintained and can prevent private information from being divulged. In another example, various embodiments of the present disclosure can learn, improve, and/or be refined over time. 
     Social Networking System—Example Implementation 
       FIG. 6  illustrates a network diagram of an example system  600  that can be utilized in various scenarios, in accordance with an embodiment of the present disclosure. The system  600  includes one or more user devices  610 , one or more external systems  620 , a social networking system (or service)  630 , and a network  650 . In an embodiment, the social networking service, provider, and/or system discussed in connection with the embodiments described above may be implemented as the social networking system  630 . For purposes of illustration, the embodiment of the system  600 , shown by  FIG. 6 , includes a single external system  620  and a single user device  610 . However, in other embodiments, the system  600  may include more user devices  610  and/or more external systems  620 . In certain embodiments, the social networking system  630  is operated by a social network provider, whereas the external systems  620  are separate from the social networking system  630  in that they may be operated by different entities. In various embodiments, however, the social networking system  630  and the external systems  620  operate in conjunction to provide social networking services to users (or members) of the social networking system  630 . In this sense, the social networking system  630  provides a platform or backbone, which other systems, such as external systems  620 , may use to provide social networking services and functionalities to users across the Internet. 
     The user device  610  comprises one or more computing devices (or systems) that can receive input from a user and transmit and receive data via the network  650 . In one embodiment, the user device  610  is a conventional computer system executing, for example, the Microsoft Windows® operating system (OS), the Apple OS X® operating system, and/or a Linux® distribution. In another embodiment, the user device  610  can be a device having computer functionality, such as a smart-phone, a tablet, a personal digital assistant (PDA), a mobile telephone, a laptop computer, a wearable device (e.g., a pair of glasses, a watch, a bracelet, etc.), a camera, an appliance, etc. The user device  610  is configured to communicate via the network  650 . The user device  610  can execute an application, for example, a browser application that allows a user of the user device  610  to interact with the social networking system  630 . In another embodiment, the user device  610  interacts with the social networking system  630  through an application programming interface (API) provided by the native operating system of the user device  610 , such as iOS and ANDROID™. The user device  610  is configured to communicate with the external system  620  and the social networking system  630  via the network  650 , which may comprise any combination of local area and/or wide area networks, using wired and/or wireless communication systems. 
     In one embodiment, the network  650  uses standard communications technologies and protocols. Thus, the network  650  can include links using technologies such as Ethernet, 802.11, worldwide interoperability for microwave access (WiMAX), 3G, 4G, CDMA, GSM, LTE, digital subscriber line (DSL), etc. Similarly, the networking protocols used on the network  650  can include multiprotocol label switching (MPLS), transmission control protocol/Internet protocol (TCP/IP), User Datagram Protocol (UDP), hypertext transport protocol (HTTP), simple mail transfer protocol (SMTP), file transfer protocol (FTP), and the like. The data exchanged over the network  650  can be represented using technologies and/or formats including hypertext markup language (HTML) and extensible markup language (XML). In addition, all or some links can be encrypted using conventional encryption technologies such as secure sockets layer (SSL), transport layer security (TLS), and Internet Protocol security (IPsec). 
     In one embodiment, the user device  610  may display content from the external system  620  and/or from the social networking system  630  by processing a markup language document  614  received from the external system  620  and from the social networking system  630  using a browser application  612 . The markup language document  614  identifies content and one or more instructions describing formatting or presentation of the content. By executing the instructions included in the markup language document  614 , the browser application  612  displays the identified content using the format or presentation described by the markup language document  614 . For example, the markup language document  614  includes instructions for generating and displaying a web page having multiple frames that include text and/or image data retrieved from the external system  620  and the social networking system  630 . In various embodiments, the markup language document  614  comprises a data file including extensible markup language (XML) data, extensible hypertext markup language (XHTML) data, or other markup language data. Additionally, the markup language document  614  may include JavaScript Object Notation (JSON) data, JSON with padding (JSONP), and JavaScript data to facilitate data-interchange between the external system  620  and the user device  610 . The browser application  612  on the user device  610  may use a JavaScript compiler to decode the markup language document  614 . 
     The markup language document  614  may also include, or link to, applications or application frameworks such as FLASH™ or Unity™ applications, the Silverlight™ application framework, etc. 
     In one embodiment, the user device  610  also includes one or more cookies  616  including data indicating whether a user of the user device  610  is logged into the social networking system  630 , which may enable modification of the data communicated from the social networking system  630  to the user device  610 . 
     The external system  620  includes one or more web servers that include one or more web pages  622   a ,  622   b , which are communicated to the user device  610  using the network  650 . The external system  620  is separate from the social networking system  630 . For example, the external system  620  is associated with a first domain, while the social networking system  630  is associated with a separate social networking domain. Web pages  622   a ,  622   b , included in the external system  620 , comprise markup language documents  614  identifying content and including instructions specifying formatting or presentation of the identified content. As discussed previously, it should be appreciated that there can be many variations or other possibilities. 
     The social networking system  630  includes one or more computing devices for a social network, including a plurality of users, and providing users of the social network with the ability to communicate and interact with other users of the social network. In some instances, the social network can be represented by a graph, i.e., a data structure including edges and nodes. Other data structures can also be used to represent the social network, including but not limited to databases, objects, classes, meta elements, files, or any other data structure. The social networking system  630  may be administered, managed, or controlled by an operator. The operator of the social networking system  630  may be a human being, an automated application, or a series of applications for managing content, regulating policies, and collecting usage metrics within the social networking system  630 . Any type of operator may be used. 
     Users may join the social networking system  630  and then add connections to any number of other users of the social networking system  630  to whom they desire to be connected. As used herein, the term “friend” refers to any other user of the social networking system  630  to whom a user has formed a connection, association, or relationship via the social networking system  630 . For example, in an embodiment, if users in the social networking system  630  are represented as nodes in the social graph, the term “friend” can refer to an edge formed between and directly connecting two user nodes. 
     Connections may be added explicitly by a user or may be automatically created by the social networking system  630  based on common characteristics of the users (e.g., users who are alumni of the same educational institution). For example, a first user specifically selects a particular other user to be a friend. Connections in the social networking system  630  are usually in both directions, but need not be, so the terms “user” and “friend” depend on the frame of reference. Connections between users of the social networking system  630  are usually bilateral (“two-way”), or “mutual,” but connections may also be unilateral, or “one-way.” For example, if Bob and Joe are both users of the social networking system  630  and connected to each other, Bob and Joe are each other&#39;s connections. If, on the other hand, Bob wishes to connect to Joe to view data communicated to the social networking system  630  by Joe, but Joe does not wish to form a mutual connection, a unilateral connection may be established. The connection between users may be a direct connection; however, some embodiments of the social networking system  630  allow the connection to be indirect via one or more levels of connections or degrees of separation. 
     In addition to establishing and maintaining connections between users and allowing interactions between users, the social networking system  630  provides users with the ability to take actions on various types of items supported by the social networking system  630 . These items may include groups or networks (i.e., social networks of people, entities, and concepts) to which users of the social networking system  630  may belong, events or calendar entries in which a user might be interested, computer-based applications that a user may use via the social networking system  630 , transactions that allow users to buy or sell items via services provided by or through the social networking system  630 , and interactions with advertisements that a user may perform on or off the social networking system  630 . These are just a few examples of the items upon which a user may act on the social networking system  630 , and many others are possible. A user may interact with anything that is capable of being represented in the social networking system  630  or in the external system  620 , separate from the social networking system  630 , or coupled to the social networking system  630  via the network  650 . 
     The social networking system  630  is also capable of linking a variety of entities. For example, the social networking system  630  enables users to interact with each other as well as external systems  620  or other entities through an API, a web service, or other communication channels. The social networking system  630  generates and maintains the “social graph” comprising a plurality of nodes interconnected by a plurality of edges. Each node in the social graph may represent an entity that can act on another node and/or that can be acted on by another node. The social graph may include various types of nodes. Examples of types of nodes include users, non-person entities, content items, web pages, groups, activities, messages, concepts, and any other things that can be represented by an object in the social networking system  630 . An edge between two nodes in the social graph may represent a particular kind of connection, or association, between the two nodes, which may result from node relationships or from an action that was performed by one of the nodes on the other node. In some cases, the edges between nodes can be weighted. The weight of an edge can represent an attribute associated with the edge, such as a strength of the connection or association between nodes. Different types of edges can be provided with different weights. For example, an edge created when one user “likes” another user may be given one weight, while an edge created when a user befriends another user may be given a different weight. 
     As an example, when a first user identifies a second user as a friend, an edge in the social graph is generated connecting a node representing the first user and a second node representing the second user. As various nodes relate or interact with each other, the social networking system  630  modifies edges connecting the various nodes to reflect the relationships and interactions. 
     The social networking system  630  also includes user-generated content, which enhances a user&#39;s interactions with the social networking system  630 . User-generated content may include anything a user can add, upload, send, or “post” to the social networking system  630 . For example, a user communicates posts to the social networking system  630  from a user device  610 . Posts may include data such as status updates or other textual data, location information, images such as photos, videos, links, music or other similar data and/or media. Content may also be added to the social networking system  630  by a third party. Content “items” are represented as objects in the social networking system  630 . In this way, users of the social networking system  630  are encouraged to communicate with each other by posting text and content items of various types of media through various communication channels. Such communication increases the interaction of users with each other and increases the frequency with which users interact with the social networking system  630 . 
     The social networking system  630  includes a web server  632 , an API request server  634 , a user profile store  636 , a connection store  638 , an action logger  640 , an activity log  642 , and an authorization server  644 . In an embodiment of the invention, the social networking system  630  may include additional, fewer, or different components for various applications. Other components, such as network interfaces, security mechanisms, load balancers, failover servers, management and network operations consoles, and the like are not shown so as to not obscure the details of the system. 
     The user profile store  636  maintains information about user accounts, including biographic, demographic, and other types of descriptive information, such as work experience, educational history, hobbies or preferences, location, and the like that has been declared by users or inferred by the social networking system  630 . This information is stored in the user profile store  636  such that each user is uniquely identified. The social networking system  630  also stores data describing one or more connections between different users in the connection store  638 . The connection information may indicate users who have similar or common work experience, group memberships, hobbies, or educational history. Additionally, the social networking system  630  includes user-defined connections between different users, allowing users to specify their relationships with other users. For example, user-defined connections allow users to generate relationships with other users that parallel the users&#39; real-life relationships, such as friends, co-workers, partners, and so forth. Users may select from predefined types of connections, or define their own connection types as needed. Connections with other nodes in the social networking system  630 , such as non-person entities, buckets, cluster centers, images, interests, pages, external systems, concepts, and the like are also stored in the connection store  638 . 
     The social networking system  630  maintains data about objects with which a user may interact. To maintain this data, the user profile store  636  and the connection store  638  store instances of the corresponding type of objects maintained by the social networking system  630 . Each object type has information fields that are suitable for storing information appropriate to the type of object. For example, the user profile store  636  contains data structures with fields suitable for describing a user&#39;s account and information related to a user&#39;s account. When a new object of a particular type is created, the social networking system  630  initializes a new data structure of the corresponding type, assigns a unique object identifier to it, and begins to add data to the object as needed. This might occur, for example, when a user becomes a user of the social networking system  630 , the social networking system  630  generates a new instance of a user profile in the user profile store  636 , assigns a unique identifier to the user account, and begins to populate the fields of the user account with information provided by the user. 
     The connection store  638  includes data structures suitable for describing a user&#39;s connections to other users, connections to external systems  620  or connections to other entities. The connection store  638  may also associate a connection type with a user&#39;s connections, which may be used in conjunction with the user&#39;s privacy setting to regulate access to information about the user. In an embodiment of the invention, the user profile store  636  and the connection store  638  may be implemented as a federated database. 
     Data stored in the connection store  638 , the user profile store  636 , and the activity log  642  enables the social networking system  630  to generate the social graph that uses nodes to identify various objects and edges connecting nodes to identify relationships between different objects. For example, if a first user establishes a connection with a second user in the social networking system  630 , user accounts of the first user and the second user from the user profile store  636  may act as nodes in the social graph. The connection between the first user and the second user stored by the connection store  638  is an edge between the nodes associated with the first user and the second user. Continuing this example, the second user may then send the first user a message within the social networking system  630 . The action of sending the message, which may be stored, is another edge between the two nodes in the social graph representing the first user and the second user. Additionally, the message itself may be identified and included in the social graph as another node connected to the nodes representing the first user and the second user. 
     In another example, a first user may tag a second user in an image that is maintained by the social networking system  630  (or, alternatively, in an image maintained by another system outside of the social networking system  630 ). The image may itself be represented as a node in the social networking system  630 . This tagging action may create edges between the first user and the second user as well as create an edge between each of the users and the image, which is also a node in the social graph. In yet another example, if a user confirms attending an event, the user and the event are nodes obtained from the user profile store  636 , where the attendance of the event is an edge between the nodes that may be retrieved from the activity log  642 . By generating and maintaining the social graph, the social networking system  630  includes data describing many different types of objects and the interactions and connections among those objects, providing a rich source of socially relevant information. 
     The web server  632  links the social networking system  630  to one or more user devices  610  and/or one or more external systems  620  via the network  650 . The web server  632  serves web pages, as well as other web-related content, such as Java, JavaScript, Flash, XML, and so forth. The web server  632  may include a mail server or other messaging functionality for receiving and routing messages between the social networking system  630  and one or more user devices  610 . The messages can be instant messages, queued messages (e.g., email), text and SMS messages, or any other suitable messaging format. 
     The API request server  634  allows one or more external systems  620  and user devices  610  to call access information from the social networking system  630  by calling one or more API functions. The API request server  634  may also allow external systems  620  to send information to the social networking system  630  by calling APIs. The external system  620 , in one embodiment, sends an API request to the social networking system  630  via the network  650 , and the API request server  634  receives the API request. The API request server  634  processes the request by calling an API associated with the API request to generate an appropriate response, which the API request server  634  communicates to the external system  620  via the network  650 . For example, responsive to an API request, the API request server  634  collects data associated with a user, such as the user&#39;s connections that have logged into the external system  620 , and communicates the collected data to the external system  620 . In another embodiment, the user device  610  communicates with the social networking system  630  via APIs in the same manner as external systems  620 . 
     The action logger  640  is capable of receiving communications from the web server  632  about user actions on and/or off the social networking system  630 . The action logger  640  populates the activity log  642  with information about user actions, enabling the social networking system  630  to discover various actions taken by its users within the social networking system  630  and outside of the social networking system  630 . Any action that a particular user takes with respect to another node on the social networking system  630  may be associated with each user&#39;s account, through information maintained in the activity log  642  or in a similar database or other data repository. Examples of actions taken by a user within the social networking system  630  that are identified and stored may include, for example, adding a connection to another user, sending a message to another user, reading a message from another user, viewing content associated with another user, attending an event posted by another user, posting an image, attempting to post an image, or other actions interacting with another user or another object. When a user takes an action within the social networking system  630 , the action is recorded in the activity log  642 . In one embodiment, the social networking system  630  maintains the activity log  642  as a database of entries. When an action is taken within the social networking system  630 , an entry for the action is added to the activity log  642 . The activity log  642  may be referred to as an action log. 
     Additionally, user actions may be associated with concepts and actions that occur within an entity outside of the social networking system  630 , such as an external system  620  that is separate from the social networking system  630 . For example, the action logger  640  may receive data describing a user&#39;s interaction with an external system  620  from the web server  632 . In this example, the external system  620  reports a user&#39;s interaction according to structured actions and objects in the social graph. 
     Other examples of actions where a user interacts with an external system  620  include a user expressing an interest in an external system  620  or another entity, a user posting a comment to the social networking system  630  that discusses an external system  620  or a web page  622   a  within the external system  620 , a user posting to the social networking system  630  a Uniform Resource Locator (URL) or other identifier associated with an external system  620 , a user attending an event associated with an external system  620 , or any other action by a user that is related to an external system  620 . Thus, the activity log  642  may include actions describing interactions between a user of the social networking system  630  and an external system  620  that is separate from the social networking system  630 . 
     The authorization server  644  enforces one or more privacy settings of the users of the social networking system  630 . A privacy setting of a user determines how particular information associated with a user can be shared. The privacy setting comprises the specification of particular information associated with a user and the specification of the entity or entities with whom the information can be shared. Examples of entities with which information can be shared may include other users, applications, external systems  620 , or any entity that can potentially access the information. The information that can be shared by a user comprises user account information, such as profile photos, phone numbers associated with the user, user&#39;s connections, actions taken by the user such as adding a connection, changing user profile information, and the like. 
     The privacy setting specification may be provided at different levels of granularity. For example, the privacy setting may identify specific information to be shared with other users; the privacy setting identifies a work phone number or a specific set of related information, such as, personal information including profile photo, home phone number, and status. Alternatively, the privacy setting may apply to all the information associated with the user. The specification of the set of entities that can access particular information can also be specified at various levels of granularity. Various sets of entities with which information can be shared may include, for example, all friends of the user, all friends of friends, all applications, or all external systems  620 . One embodiment allows the specification of the set of entities to comprise an enumeration of entities. For example, the user may provide a list of external systems  620  that are allowed to access certain information. Another embodiment allows the specification to comprise a set of entities along with exceptions that are not allowed to access the information. For example, a user may allow all external systems  620  to access the user&#39;s work information, but specify a list of external systems  620  that are not allowed to access the work information. Certain embodiments call the list of exceptions that are not allowed to access certain information a “block list”. External systems  620  belonging to a block list specified by a user are blocked from accessing the information specified in the privacy setting. Various combinations of granularity of specification of information, and granularity of specification of entities, with which information is shared are possible. For example, all personal information may be shared with friends whereas all work information may be shared with friends of friends. 
     The authorization server  644  contains logic to determine if certain information associated with a user can be accessed by a user&#39;s friends, external systems  620 , and/or other applications and entities. The external system  620  may need authorization from the authorization server  644  to access the user&#39;s more private and sensitive information, such as the user&#39;s work phone number. Based on the user&#39;s privacy settings, the authorization server  644  determines if another user, the external system  620 , an application, or another entity is allowed to access information associated with the user, including information about actions taken by the user. 
     In some embodiments, the social networking system  630  can include an entity module  646 . The entity module  646  can, for example, be implemented as the entity module  102  of  FIG. 1 . As discussed previously, it should be appreciated that there can be many variations or other possibilities. 
     Hardware Implementation 
     The foregoing processes and features can be implemented by a wide variety of machine and computer system architectures and in a wide variety of network and computing environments.  FIG. 7  illustrates an example of a computer system  700  that may be used to implement one or more of the embodiments described herein in accordance with an embodiment of the invention. The computer system  700  includes sets of instructions for causing the computer system  700  to perform the processes and features discussed herein. The computer system  700  may be connected (e.g., networked) to other machines. In a networked deployment, the computer system  700  may operate in the capacity of a server machine or a client machine in a client-server network environment, or as a peer machine in a peer-to-peer (or distributed) network environment. In an embodiment of the invention, the computer system  700  may be the social networking system  630 , the user device  610 , and the external system  720 , or a component thereof. In an embodiment of the invention, the computer system  700  may be one server among many that constitutes all or part of the social networking system  630 . 
     The computer system  700  includes a processor  702 , a cache  704 , and one or more executable modules and drivers, stored on a computer-readable medium, directed to the processes and features described herein. Additionally, the computer system  700  includes a high performance input/output (I/O) bus  706  and a standard I/O bus  708 . A host bridge  710  couples processor  702  to high performance I/O bus  706 , whereas I/O bus bridge  712  couples the two buses  706  and  708  to each other. A system memory  714  and one or more network interfaces  716  couple to high performance I/O bus  706 . The computer system  700  may further include video memory and a display device coupled to the video memory (not shown). Mass storage  718  and I/O ports  720  couple to the standard I/O bus  708 . The computer system  700  may optionally include a keyboard and pointing device, a display device, or other input/output devices (not shown) coupled to the standard I/O bus  708 . Collectively, these elements are intended to represent a broad category of computer hardware systems, including but not limited to computer systems based on the x86-compatible processors manufactured by Intel Corporation of Santa Clara, Calif., and the x86-compatible processors manufactured by Advanced Micro Devices (AMD), Inc., of Sunnyvale, Calif., as well as any other suitable processor. 
     An operating system manages and controls the operation of the computer system  700 , including the input and output of data to and from software applications (not shown). The operating system provides an interface between the software applications being executed on the system and the hardware components of the system. Any suitable operating system may be used, such as the LINUX Operating System, the Apple Macintosh Operating System, available from Apple Computer Inc. of Cupertino, Calif., UNIX operating systems, Microsoft® Windows® operating systems, BSD operating systems, and the like. Other implementations are possible. 
     The elements of the computer system  700  are described in greater detail below. In particular, the network interface  716  provides communication between the computer system  700  and any of a wide range of networks, such as an Ethernet (e.g., IEEE 802.3) network, a backplane, etc. The mass storage  718  provides permanent storage for the data and programming instructions to perform the above-described processes and features implemented by the respective computing systems identified above, whereas the system memory  714  (e.g., DRAM) provides temporary storage for the data and programming instructions when executed by the processor  702 . The I/O ports  720  may be one or more serial and/or parallel communication ports that provide communication between additional peripheral devices, which may be coupled to the computer system  700 . 
     The computer system  700  may include a variety of system architectures, and various components of the computer system  700  may be rearranged. For example, the cache  704  may be on-chip with processor  702 . Alternatively, the cache  704  and the processor  702  may be packed together as a “processor module”, with processor  702  being referred to as the “processor core”. Furthermore, certain embodiments of the invention may neither require nor include all of the above components. For example, peripheral devices coupled to the standard I/O bus  708  may couple to the high performance I/O bus  706 . In addition, in some embodiments, only a single bus may exist, with the components of the computer system  700  being coupled to the single bus. Moreover, the computer system  700  may include additional components, such as additional processors, storage devices, or memories. 
     In general, the processes and features described herein may be implemented as part of an operating system or a specific application, component, program, object, module, or series of instructions referred to as “programs”. For example, one or more programs may be used to execute specific processes described herein. The programs typically comprise one or more instructions in various memory and storage devices in the computer system  700  that, when read and executed by one or more processors, cause the computer system  700  to perform operations to execute the processes and features described herein. The processes and features described herein may be implemented in software, firmware, hardware (e.g., an application specific integrated circuit), or any combination thereof. 
     In one implementation, the processes and features described herein are implemented as a series of executable modules run by the computer system  700 , individually or collectively in a distributed computing environment. The foregoing modules may be realized by hardware, executable modules stored on a computer-readable medium (or machine-readable medium), or a combination of both. For example, the modules may comprise a plurality or series of instructions to be executed by a processor in a hardware system, such as the processor  702 . Initially, the series of instructions may be stored on a storage device, such as the mass storage  718 . However, the series of instructions can be stored on any suitable computer readable storage medium. Furthermore, the series of instructions need not be stored locally, and could be received from a remote storage device, such as a server on a network, via the network interface  716 . The instructions are copied from the storage device, such as the mass storage  718 , into the system memory  714  and then accessed and executed by the processor  702 . In various implementations, a module or modules can be executed by a processor or multiple processors in one or multiple locations, such as multiple servers in a parallel processing environment. 
     Examples of computer-readable media include, but are not limited to, recordable type media such as volatile and non-volatile memory devices; solid state memories; floppy and other removable disks; hard disk drives; magnetic media; optical disks (e.g., Compact Disk Read-Only Memory (CD ROMS), Digital Versatile Disks (DVDs)); other similar non-transitory (or transitory), tangible (or non-tangible) storage medium; or any type of medium suitable for storing, encoding, or carrying a series of instructions for execution by the computer system  700  to perform any one or more of the processes and features described herein. 
     For purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of the description. It will be apparent, however, to one skilled in the art that embodiments of the disclosure can be practiced without these specific details. In some instances, modules, structures, processes, features, and devices are shown in block diagram form in order to avoid obscuring the description. In other instances, functional block diagrams and flow diagrams are shown to represent data and logic flows. The components of block diagrams and flow diagrams (e.g., modules, blocks, structures, devices, features, etc.) may be variously combined, separated, removed, reordered, and replaced in a manner other than as expressly described and depicted herein. 
     Reference in this specification to “one embodiment”, “an embodiment”, “other embodiments”, “one series of embodiments”, “some embodiments”, “various embodiments”, or the like means that a particular feature, design, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the disclosure. The appearances of, for example, the phrase “in one embodiment” or “in an embodiment” in various places in the specification are not necessarily all referring to the same embodiment, nor are separate or alternative embodiments mutually exclusive of other embodiments. Moreover, whether or not there is express reference to an “embodiment” or the like, various features are described, which may be variously combined and included in some embodiments, but also variously omitted in other embodiments. Similarly, various features are described that may be preferences or requirements for some embodiments, but not other embodiments. 
     The language used herein has been principally selected for readability and instructional purposes, and it may not have been selected to delineate or circumscribe the inventive subject matter. It is therefore intended that the scope of the invention be limited not by this detailed description, but rather by any claims that issue on an application based hereon. Accordingly, the disclosure of the embodiments of the invention is intended to be illustrative, but not limiting, of the scope of the invention, which is set forth in the following claims.