Search engines have become popular tools to identify and locate specific information on the Internet.  A search engine is a computer program that, when queried for information, retrieves either related information or pointers to the location of related information, or both, by evaluating content stored in its search database.  A key metric in evaluating the performance of search engines is relevance of the search results.  Search engine developers are always striving to deliver search results that are relevant to the search query being processed.  Consistent with this goal, there have been attempts to rank search results based on a number of different factors.  One of the more popular ways to rank search results involves analyzing the location and frequency of keywords on a webpage.  Another frequently used technique is analyzing how webpages link to each other. 
A social-networking system, which may include a social-networking website, may enable its users (such as persons or organizations) to interact with it and with each other through it.  The social-networking system may, with input from a user, create and store in the social-networking system a user profile associated with the user.  The user profile may include demographic information, communication-channel information, and information on personal interests of the user.  The social-networking system may also, with input from a user, create and store a record of relationships of the user with other users of the social-networking system, as well as provide services (e.g. wall posts, photo-sharing, event organization, messaging, games, or advertisements) to facilitate social interaction between or among users.