What is DC (it is at almost every spell or skill description?

It is the Difficulty Class. It's a measure of how hard it is to circumvent, or not be affected by whatever it is.

For example, lets take a trap. If it has a DC of 35, you need to get a 35 or better by rolling a d20 and applying any modifiers (disarm trap skill ranks etc.) in order to successfuly disarm the trap.

actuelly i found a door that had a lock on it that was DC100 in chap 1 i think it was :p
that I think that is almost imposible to unlock :p
so ofcourse i just bashed it down :lol:
i'm guessing the lock was supose to be dc10 but someone goofed :)

Knock Knock :p

Actually Syrel, there are some doors like that because you weren't really intended to go past them. Of course, you did anyway.

Bioware did put that in there to actually make some unlockable doors.

Until I got to chapter 2 I totally forgot about bashing and I just let Tomi unlock doors and chests and when he couldn't do it I just left and went on. When I got too chapter 2 I remembered bashing and I was pissed at myself for how much stuff I missed.