Social networks are a recent trend. Social networking sites (SNS) connect and present people based on information based on them and stored as their user profiles. The user profile determines the way in which the user is able to present themselves to others. The most important distinguishing factor is the range of profile information each of the different sites present. This paper presents a review of the various classification of social networking portals whether they are registration or connection based, whether user profiles are social or professionally oriented and if explicit relationships can be defined; whether sites are non-profit or profit-based.
