Social networking sites (SNS) refer to internet-based services that give individuals three major capabilities:

1. The ability to construct a public or semi-public profile.
2. The ability to identify a list of other users with whom a connection is shared.
3. The ability to view and track individual connections as well as those made by others.

The use of Facebook varies according to a user’s gender (1), ethnicity (2) and parental educational background (3). There are several characteristics of Facebook usage for people who score high on extraversion:

• They are more likely to use Facebook as a social tool but not as an alternative to social activities.
• They use social networking sites more.
• They show addictive tendencies when using social networking sites.

These characteristics may arise due to extraverted people’s need for a high level of stimulation and a large social network. Introverted people tend to transfer their socially inhibited behavioural style from offline to online. They have fewer Facebook friends but tend to spend more time on Facebook and have a more favourable attitude towards Facebook.

People who score high on neuroticism prefer the wall function and share more basic information. People who score low on neuroticism also share more basic information but not people with a moderate score. People with greater openness to experience use more features form the personal information section. People with high narcissism and low self-esteem tend to spend more time on Facebook. They are also more likely to post self-promotional photos enhanced by Photoshop.

The tendency to disclose and the need for popularity are predictors of information disclosure on Facebook. Facebook use is predicted by high levels of extraversion (1), neuroticism (2) and narcissism (3), low levels of self-esteem (4) and self-worth (5).

The dual-factor model of Facebook use states that Facebook use is primarily motivated by the need to belong and the need for self-presentation. The need to belong refers to the intrinsic drive to affiliate with others and gain social acceptance. The need for self-presentation refers to the continuous process of impression management.

Self-esteem and self-worth are closely associated with the need to belong. Self-esteem may play the role of monitoring one’s acceptability in the group (e.g. drop in self-esteem motivates steps to avoid rejection and improve standing of social hierarchy).

Exposure to information presented on one’s Facebook profile enhances self-esteem. This is especially the case when selectively self-presenting (e.g. editing information). Facebook use intensity reduces students’ perceived levels of loneliness. However, it is not clear whether Facebook use improves self-esteem as results are mixed.

Facebook use may facilitate relationship development and acceptance of peers. The association between Facebook use and self-esteem may be moderated by cultural and social factors. A general disconnection appears to motivate Facebook use and being connected appears to reward Facebook use.

The idealized-virtual identity hypothesis states that social media allows users to display their idealized rather than accurate self through their profile. However, profiles appear to portray real personality rather than solely enhanced personality. A Facebook impression appears to be an accurate predictor of offline impressions. Emotional stability cannot be accurately assessed by looking at a Facebook profile. It is also possible that Facebook selves are socially desirable and reflect the self one wishes to have. Social expressivity is the trait that creates a positive impression of both online and offline profiles.

Attractive friends on a Facebook profile create more positive impressions. Attractiveness is important in forming impressions about others. A low number of friends or a very high number of friends cast doubts about a user’s popularity and desirability. This is shaped and motivated by the need for self-presentation as this need guides users’ specific behaviours (e.g. profile photo choice).

Demographic and cultural values contribute to the need to belong. Personality factors (i.e. neuroticism, narcissism, shyness, self-esteem and self-worth) contribute to the need for self-presentation.