What does backing up mean?

Question

in itunes when syncing with my iphone 3G it says its backing it up. what does this mean and what is it doing?

Answer 1

I'm pretty sure that means that it is downloading an image of the iphones hard drive.  That way, if your phone should have any error problem that causes the information to go bad and stop working, you can connect it to the computer, the backup will restore and it will go back to exactly how it was when you "backed it up".