The World Wide Web is a powerful tool. It helps people to communicate and connect in ways that weren't possible a few decades ago. You can chat with friends across the globe, share photos and videos while you catch up with each other. With the help of Web, you are able to track down an old friend whom you've not seen or met in years. It also allows you to make new friends or even find your soul mate. A social networking service is a platform to build social relations amidst people who share same interests, activities, backgrounds, or real-life connections. A social network service consists of a profile of each user which represents him or her, his or her social links, and a variety of additional services. The social networking sites provide a medium for users to interact over the Internet, such as e-mail and instant messaging or wall posts. Online social networking sites are some of the most popular online destinations now. These sites package services together in a compact and attractive way so that users can exert the Web to make connections with others. There are a few hundreds of social networking sites.