Wikipedia: Mouse gestures

Mouse gestures provide quick access to common functions of a computer application. The user moves his mouse in certain predefined ways, usually while holding down a button or key on his keyboard. For example, in a web browser, the user could navigate to the previously viewed page by clicking the right mouse button and moving his mouse to the left, then releasing the button. The way the gestures are recognized is different with each implementation, sometimes allowing for very short mouse movement distances to be recognized as gestures, and sometimes requiring very exact emulation of a certain movement pattern (e.g. circle). Some implementations allow user customization of these factors.

Some computer and video games have used mouse gestures. For example, in the Myth real-time? strategy series, originally created by Bungie Software, players use them to order battlefield units to move in a desired direction.