Social network has become an important part of every individual's daily routine. Social Networking Sites (SNS) like Twitter, Facebook, LinkedIn and Google+ are user interfaces for social network which can be accessed through internet and web 2. 0 technologies. It provides a platform for its users, where they connect, communicate, share, update etc. People are developing more interest for social networks as there is dependency for information, news, daily updates and psychology of other humans on a generalized scenario is easily available with a ease of access. With this increasing use and interest of any SNS a lot more enhancement and more utility can be provided for its users which is a crucial and a tedious area of interest for researchers with growing trend and demand. In this paper a attempt is made to summarize basic ideas behind a Social Network and working of a SNS with some existing work done and areas where there is scope of improvement by categorizing the research topics for a online social network.

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Social Network Social Networking Sites Community Social Connection.