I have been using Facebook from last 6-7 years. Before that I was using Google’s Orkut. I moved to Facebook since many of the friends was active on it. At that time facebook’s user interface was different. Creating account on facebook is free and simple process.
Your should be of 14 years age and should have email account. I mainly use facebook to chat with my friends. Apart from chatting I use facebook for news feed, express my opinions through facebook wall, to comment on cricket pages, and several groups. I also use facebook to share recent photos and videos with my friends.
The problem with facebook is that anyone can easily get addicted with it. Apart from that you need decent internet connection to fully load facebook as it is very much heavy website. Online experience is very nice. Any one can share his/her thoughts/opinions through facebook wall. You can also promote your own business through facebook page service.