What is Vertical Sync and Screen Tearing?

Vertical Sync is a method that the game uses to stop "screen tearing" which is when the screen seems to get chopped up into 2 or more pieces and items in the game seem to be split in half and then one piece is moved around.

Basically imagine you took a ball of chocolate, sliced it in half, and then moved one of the halves off center.

Vertical Syncing is supposed to fix this problem, but most computers don't require this option on. Generally you should keep it off since it decreases your FPS in most cases, but if you start seeing screen tearing going on, you should probably turn it back on.