.There personal info. status updates etc
.you can make it so just your friends can see it or you can make it so your friends and there friends can see it or you can let everyone see it.
.it can be very dangerous to let everyonne see your facebook you can gte stocked you can get fired from your job or other bad things like that.
Its good but only when its used the right way it can be a very dangerous thing when used the wrong way.