ClockworkMod Recovery

Hey everyone :D

This will be my first time flashing a custom rom onto my Samsung GS3 i9300. I am putting CM10.1. But i want to use clockworkmod to backup my phone.

My question is, when you say "backup" in clockwork does it back up Touchwiz in my case, or just apps/ personal data? I want to be able to return to Touchwiz if i have any problems. Is this possible with just doing a restore through clockworkmod?

Any help would be appreciated.