First SNS was SixDegrees.com which was launched in 1997. Some most commonly SNSs used today are: Facebook, Google plus, Twitter, Flickr, Bebo, MySpace, Meetup, Meetme, Orkut, etc. Users create their profiles, add interests, add photographs, add friends, etc. Here friends can be relatives, colleagues, or even strangers. Friends can be added from anywhere in the world.
SNSs have become common among children, teenage, adults, and also among old people. It is a very common pastime and also the most convinent means to connect to the people, whom we can't meet or connect through phone. We can also video chat, voice chat, or do video conferencing with the friends added in our friend's list. This is the most important feature provided by such sites. Even jobs can be searched on these sites; Linkedin is the professional networking site of one such type. There are SNSs for dogs and cats also, Dogster and Catster respectively. Their profiles are managed by their owners.
SNSs sites are extensively used by youth; not only by college and school going kids but also people working in office. It kills valuable time, intended for productive work. These sites are blocked in several offices and also schools and colleges, but there are various proxy servers which can be used to access these sites. These sites are also involved in Cyber Crime.
Technology has their own advantages and disadvantages. Thus, these sites are again the gift of Science & Technology if used with great...