[absolute]

I was playing on a sniper only server a while back and was accused of wall hacking. It was a dedicated server but one of the admin's said he was watching me do this wall hacking and then he banned me permanantly and said if anyone from my clan came on, they'd ban them too.
Well, all fair I suppose if i even knew what wallhacking was. I mean, I was having a good day and I definitely wasn't cheating.
My question is..what is wall hacking?
I guess i'd just like to know what i was being acused of.