Lot of Social networking sites now.Right from Orkut, Myspace,tagged, Google plus etc etc .But still Facebook till now atleast is leading the race.The reasons are as follows :
People need their own space.But at the same time, they don't want to keep it private.Wall gives people the thing they always want to do - SHOW OFF !!!
Well, tats true.Publish photos,status updates,links etc and then keep eye on top left notifications for likes and comments.
"Just saw the movie xyz ", " Today had an awesome day thanks to ed , mark and zack " , " Go Nadal Go ".
Another utility of facebook which allows people seek attention.Nowadays, Tweeter has been more dedicated to Celebs,Sportstars etc. So everyone is happy with posting status updates from their day to day life or even sports or other worldly events.Even if no one follows your status, they are sure to like and comment on it .
Thats part of Facebook Addiction literally.Like this page,Like this comment,status,photo,video n so on.
One of the most important thing,which cause people to switch from other networking sites like orkut to facebook.Many of the apps are really lame, but people are crazy abt them= android apps,iphone apps etc.Use an app, post the results and displayed them on your wall.
Flash games look childish and easy.But they are very good at keeping u hooked up on them.In few mins, you will be addicted to them , lost track of time and inviting your friends to join the venture.Zyanga games like Mafia Wars,UNO,Farmville,Racing etc satisfy your busy gaming needs.Also you can play a variety of games with your friends online.
Thus,Facebook is ruling because it has the right blend of activities and provides a platform for people to present and promote themselves in a better way(in short Show OFF :P )