I'm a newbie to DIY audio, and after looking pretty thoroughly through tangentsoft's tutorial on building a Cmoy (which is what im going to be trying to do), I've heard a lot of mention on op-amp "clipping". What exactly does this mean for an op-amp to be clipping?

I'm building a Cmoy amp as introduction to DIY audio. I bought a potentiometer from radioshack that includes SPDT power (when turned all the way counterclockwise, it clicks "off"). If anyone is familiar with setting these up, I have a few questions i would greatly appreciate any help with...