A social networking service is actually an online service. There are a good number of social networking services such as Facebook. Twitter, Linkedin, YouTube, Skyrock, Friendster, Orkut,Skype etc.Among these, now facebook is the most popular social networking service.All kinds of social networking services are web based. These services have made it possible to connect people sharing interests and activities across the borders. The users of social networks feel that they really live in a global village. Nowadays, social networks are expanding so fast. Because, most of the social services are cost-free. We can use these social networks paying only a very little to internet service provider. We can exhibit our personal profile before the entire online community. It is really like presenting ourselves before the entire world. We can aslo look into other people's profile if we are interested. Besides these, social networks allow users to upload pictures, multimedia contents and modify the profile. There are privacy protection measures for the users as well. A users can select the number of his friends or the visitors of his profile etc. In fact, today using social network has become a part of modern life. Now people do not need computer for using these network services. In most mobile phone sets there are the options to get connected with social network.