I registered only on facebook. I use my account to chat with friends, to see their photos, to know news, to see beautiful or funny images and to know interesting information and facts. Some people also play games on facebook, but I don’t like these games, so I don’t play. I think that facebook is useful social network. But the other social networks are just different copies of it, so i think that to register more than on one social network is just waste of time.