The term "social media" refers to Internet-based applications that enable people to communicate and share resources and information. Some examples of social media include blogs, discussion forums, chat rooms, wikis, YouTube channels, LinkedIn, Instagram, Facebook, and Twitter. Social media can be accessed by computers, tablets, smart and cellular telephones, and mobile telephone text messaging (SMS). The use of social media is an evolving phenomenon. Rapid changes in communication technologies in the past decade have enabled people to interact and share information through media that were non-existent or widely unavailable as recently as 15 years ago. In the last 10 years social media has played an increasing role in emergencies and disasters in both the public and private sectors. Facebook hosts numerous emergency-related organizations, including Information Systems for Crisis Response and Management (ISCRAM), and the Humanitarian Free and Open Source Software (FOSS) Project. Additionally, numerous emergency and disaster-related organizations, including universities, the private and nonprofit sectors, and state and local governments use Facebook to disseminate information, communicate with each other, and coordinate activities such as emergency planning and exercises. There is also evidence that social media is increasingly being used at the community and household level to respond to emergencies and crises. A study conducted in 2012 by the American Red Cross found that 40% of the respondents said they would use social tools to tell others they were safe. That percentage is most likely higher today given the rapid proliferation and acceptance of social media in recent years. Other examples of community and household use of the media include warning others of unsafe areas or situations, creating ad hoc volunteer response groups, and raising funds for disaster relief and recovery efforts. Perhaps one of the greatest benefits of social media is that it allows people to communicate when traditional lines of communication are unavailable. For example, when power or landline service is interrupted, people generally continue to have access to information—at least on a limited basis—through social media platforms with SMS and Global Positioning Satellite (GPS) frameworks, such as Twitter. Thus, certain elements of social media can remain viable during catastrophic events when traditional forms of communication are rendered unusable. The use of social media for emergencies and disasters can be conceptualized as two broad categories of usage. First, social media can be used as an output to disseminate public safety related information. Second, social media can be used as an emergency management tool through the use of inputs. Some examples of using social media as an emergency management tool include using the medium to conduct emergency communications and issue real time warnings; using social media to receive requests for assistance; monitoring user activities and postings to establish situational awareness; using uploaded images to create damage estimates; and using social media to conduct investigations and post-incident analysis. Social media sources have a broad range of applications in emergencies and disasters. The following sections provide examples of the ways in which social media are being used. Not all of these examples are from the federal government nor are they all governmental. Additionally, federal usage of social media varies from agency to agency just as its use varies from non-governmental entity to non-governmental entity. The following is not an exhaustive list and some of the examples may change or quickly become outdated due to advances in social media. Social media are often used by emergency management organizations to coordinate and send out notifications of upcoming training events and exercises. Notifications can also be sent to mobilize first responders to respond to an incident. Using social media for mobilization purposes can be particularly useful when traditional call systems fail. For instance, during Hurricane Gustav, a Community Emergency Response Team (CERT) used social media to send mass email notifications to team members through Facebook when its call notification system went down. The CERT group also updated status messages to notify first responders and citizens of developments as the incident unfolded. Social media has been used to disseminate a wide range of public safety information before, during, and after various incidents. Prior to an incident (or in the absence of an incident), many organizations and agencies provide citizens with preparedness and readiness information through social media. For example, the Department of Health and Human Services (HHS) used Twitter to provide information on Zika virus prevention. Social media are also used for community outreach and customer service purposes by soliciting feedback on public safety-related topics. Social media is often used by organizations to provide key public safety information during emergency situations. Further, social media is being increasingly used to provide "real-time" updates as the event unfolds. For example, Orlando authorities used social media to inform the public on the shootings in the Pulse nightclub. Another example is a stream of tweets issued by the Boston Police Department to keep citizens up to date in real-time throughout the Boston Marathon bombings and subsequent manhunt. The Boston Police Department also used social media to address and correct instances of misinformation. The National Weather Service (NWS) also used social media to alert citizens in Massachusetts of road conditions during the 2015 snowstorms. Similarly, the U.S. Geological Survey launched a pair of Twitter feeds to give out automated, real-time river levels and rainfall amounts during heavy rains in response to floods in Texas. The platform automatically Tweets out river gauge levels and flow rates when they hit the flood stage. It also includes searchable hashtags and links to more information on the agency's website. Emergency alerts used at the federal level include the Federal Communications Commission (FCC) Personal Localized Alerting Network known as "PLAN" (technically the Commercial Mobile Alert System, or CMAS). Implemented in 2011, PLAN expands the emergency alert system notifications sent over TV and radio to include mobile and smart phones. PLAN sends geographically targeted alerts through cell towers in the form of text-like messages to the cell phones of people who have requested to be notified in the event of an emergency. PLAN enables government officials to target emergency alerts to specific geographic areas, which then push the information to dedicated receivers with PLAN-enabled mobile devices. The Federal Emergency Management Agency (FEMA) oversees development and operation of the Integrated Public Alert and Warnings System (IPAWS), a national system for delivering emergency alerts and warnings to the public. Today, over 150 entities—including approximately 75 counties, 25 states, and the Commonwealth of Puerto Rico—have access to the IPAWS-OPEN gateway, which allows them to transmit messages to cellular phones (using Wireless Emergency Alerts or WEA), radio and television (using the Emergency Alert System), and National Oceanic and Atmospheric Administration (NOAA) weather radios. In addition, the NWS can send weather alerts, and the National Center for Missing and Exploited Children can send AMBER alerts over IPAWS. In addition to alerts and messages sent by emergency management and governmental organizations, valuable crisis information is often disseminated by citizens. For example an estimated 3.5 million tweets with the hashtag #sandy were generated in 24 hours during Hurricane Sandy and roughly ten pictures per second were uploaded using Instagram. Social media can also be used by users to let family and friends know they are safe if they are near an incident or natural disaster. For example, Facebook activated a feature called "safety check" during the Paris terrorist attacks to allow users to post if they are safe or not in the area of an incident. The feature can also be used to check if others in the area are safe. The above are examples of how information is disseminated through outputs. However, social media can also use inputs to provide unique emergency and disaster information. For example, Crowdsourcing has been effectively used to provide information about a crisis or incident. Crowdsourcing consists of obtaining needed services, ideas, or content by soliciting contributions from the online community. An example of a federal government crowdsourcing tool is a U.S. Geological Survey (USGS) "Did You Feel It?" project which creates automatic intensity maps based on "felt" reports submitted online. More than 2 million reports have been filed on this website, with 40 earthquakes receiving more than 10,000 reports each. Another useful source of information during an incident are crisis maps. Crisis maps combine information scattered across the Internet along with other information and places them on a single map. Users can use the crisis map to ascertain storm paths and flood zones, as well as identify evacuation routes, shelter locations, and power outage areas. Information posted at the time of an event could be valuable later for investigative and research purposes. For example, viewers at the 2012 theater shooting in Aurora, CO, tweeted and posted messages moments before the attack took place. Forensic analysis of the information was used to construct incident timelines and retrieve first-hand accounts of the event as it unfolded. Social media is used to alert emergency managers and officials to certain situations by monitoring the flow of information from different sources during an incident. Monitoring information flows help establish "situational awareness." Situational awareness is the ability to identify, process, and comprehend critical elements of an incident or situation. At the local level, first responders can leverage social media, both to communicate and to gather and share real-time, dynamic information, to enhance situational awareness and assist in decision-making. Obtaining real-time information as an incident unfolds can help officials determine where people are located; assess victim needs; and alert citizens and first responders to changing conditions and new threats. Emergency managers can also use the information to direct certain resources to reduce damages, loss of life, or both. In some cases it might be possible to obtain this information before first responders reach the disaster area. Another benefit of social media is that it provides the public with another method to communicate with the government. While current emergency communication systems have largely been centralized via one-way communication—from the agency or organizations to individuals and communities—social media is increasingly altering emergency communications because information can flow in multiple directions (known as backchannel communications). One example of backchannel communication are requests for assistance.