I touched on it in my discussion on critical thinking, but it's definitely worth a post of it's own. Maybe I'll get to writing one.

A summary for bitcalm's readers - cognitive biases and heuristics are the mental "short cuts" we take in analyzing situations unconsciously; when we see a snake crawling near us, we jump in the air before we look to see whether that snake is dangerous or not. as the time to think about it may result in a poisonous bite. To oversimplify, we call these short cuts "cognitive biases" when they result in bad outcomes,and heuristics when they work effectively