Table 1.
Categorical definitions of social media.
| Service type | Definition | Example |
| Blog | Short for “web log”: a blog is an easy-to-publish website where bloggers (authors of blogs) post information and essays in sequential order [22]. | WordPress, Blogger |
| Microblog | A tiny blog service that allows networks of users to send short updates to each other in less than 140 characters. Microblogs are considered a platform for information dissemination, social networking, and real-time communication [22]. | Twitter, Identi |
| Social networking site | A social networking site is an online service, platform, or site that focuses on building and visualizing social networks or social relations among people, who, for example, share interests and/or activities. A social network service essentially consists of a representation of each user (often a profile), their social links, and a variety of additional services [23]. | Facebook, MySpace |
| Professional networking site | A professional networking site is a type of social network service that is focused solely on interactions and relationships related to business or a person’s professional career [24]. | LinkedIn, Sermo, Asklepios, Ozmosis, Drs Hangout, Doc2Doc |
| Thematic networking sites | Social networking sites centered on a particular theme; for example disaster response, nursing, etc. These share many aspects of, and operate as a community of practice. | Telehelp, Innocentive, 23andMe, PatientsLikeMeCureTogether |
| Wiki | Wikis are used to denote communal websites where content can be quickly and easily edited. Wikis support collaboration and information sharing; feature multimedia, such as video, slides, photographs; and allow anyone to edit or are password protected [22]. | Wikipedia, Fluwiki |
| Mashups | A website that combines data and functionality from two or more services to create a new, value-added, service [25]. | HealthMap, Google FluTrends |
| Collaborative filtering sites | A website where information is filtered or collected according to patterns. Techniques involving collaboration among multiple agents, viewpoints, and data sources are often used. These agents engage through a variety of sites, through a process called crowdsourcing, where the crowds join forces for a common purpose [26]. | Digg, Delicious |
| Media sharing sites | A hosting service that allows individuals to upload and create galleries of photos, videos, and other digital media (eg, slide presentations). The host will then store them on a server and make them either publicly or privately available. | SlideShare, YouTube, Flickr |
| Other | Multi-User Virtual Environments, also known as Virtual Worlds | Second Life |