Screen tearing

Screen tearing happens when you watch a video or play a game and the picture gets all messed up. Imagine you're drawing a picture and you're not going straight across, you're going up and down too. This is like what happens on your screen - the picture is being drawn from top to bottom by the computer, but sometimes it splits in the middle and the top and bottom parts are different. This split makes it look like there's a line in the middle of the screen where the two parts don't quite match up, and it can be really annoying when you're trying to watch or play something.