Yes. iTunes creates a backup of your iPhone when you sync, which you can then use to restore from if you need to return to a previously backed up state. This article explains what information is backed up: iPhone and iPod touch: About backups, http://support.apple.com/kb/HT1766
Thank you, but then where on the computer does it store them?
I read the link, it states that the back up is located on a Mac in Library/mobil backup. But I found no such mobil backup in my Library. 😟
It is stored in your user account Library/Application Support/MobileSync/Backup folder. It's not stored in a form you can use for anything except to restore your phone.