What is a judgement? It is a thought, often accompanied by an emotion or feeling, that is defining or declaring something or someone to be a certain way. Judgement often occurs when you are, for whatever reason, unwilling to see the truth or context of a thing. It's when you look at someone, even if that someone is you, and say "you ARE this way or that way and no other way".
Your judgements often override the humanity of a person - that person is no longer a person, but rather a conglomeration of the labels you have assigned to them.