If I sync my iPhone to iTunes does it back everything on the phone up?

I plugged my iPhone into my laptop and it automatically synced. I then went to get my phone exchanged. I'm scared that this didn't back up my phone and i won't get my contacts back. Can someone give me an answer?

Syncing and backing up are two totally different things. Syncing will get your media evened up if set up right but your personal content is not managed by itunes.

So you just screwed yourself.

Syncing: http://support.apple.com/.../kb/HT1386

Backing up: http://support.apple.com/.../kb/HT1766