Table 2.

Categories of social media features.

Number	Category	Description
1	Identity representation	Used to provide information about an individual and his or her activities to peers and are usually customizable by the participant. This is usually either in the form of user profiles or avatars
2	Communication	Enable intervention participants to communicate with one another and could be further categorized as many to many (eg, chat rooms), one to one (eg, peer emailing), and one way (eg, thumbs up or likes)
3	Peer grouping	Grouping of participants based on characteristics such as age, geographical locations, or part of the same intervention arm, while ensuring that they are aware about others in their group and with the possibility to have some form of direct or indirect communication. Groups can consist of a minimum of 2 participants ora OSN-based and non-OSN–based groups with more than 2 individuals
4	Data sharing	Enable participants of an intervention to share data about their activity, goals, or experience to either or both other participants and nonparticipants
5	Competition	Designed to introduce a competitive aspect in interventions through the use of features that enable participants to feel motivated while competing against one another (eg, social quiz)
6	Activity data viewing	Provide access to activity data of peers to participants through either regular updates (feeds and notifications) on a timely basis or enable them to compare their own data with that of their peers (eg, leaderboards)
7	Online social network (OSN)	The use of an Internet-based platform for enabling social interaction among intervention participants. OSNs can be subcategorized as either Generic and Conventional type (Facebook, mySpace, Twitter), Virtual World (SecondLife), or Purpose Designed (Yahoo Diet Diary, iWell, QuitNet, other intervention-specific proprietary OSNs). OSNs although being considered as a social media feature, usually act as a container for multiple other social media features

^aOSN: online social network.