why facebook is addictive?

Sincerly, I am not even a bit addicted to facebook. I use it because I can chat with some old friends, I find new friends fast. I use it like 2 times/week when I need. Another thing facebook is good to, is that you can use it to login everywhere you want.

At first I was using orkut then I moved to facebook and at that time it was new,so I joined it for the sake of the friends as they were also there.Then they brought good games in it and then I started playing Farmville,Mafia wars and Cafe and at that time I was playing games more than chatting in the facebook and this continued for many months and then I got too addicted to it and now I use it for networking and being in contact with friends with whom I am not able to be physically present.For now I have stopped playing games as when I play at that time I used to get too addicted to it and would always think of it while I am not in facebook also.