Surfing refers to a person or boat riding down a wave and thereby gathering speed from the downward movement. Most commonly, the term is used for a surface water sport in which the person surfing is carried along the face of a breaking ocean wave (the "surf") standing on a surfboard. Surfboards can also be used on rivers on standing waves. Both are sometimes called stand-up surfing, to distinguish it from bodyboarding, in which the individual riding the wave does not stand up on the board, and only partly raises his upper body from the board.
Two major subdivisions within contemporary stand-up surfing are reflected by the differences in surfboard design and riding style of longboarding and shortboarding. In tow-in surfing (most often, but not exclusively, associated with big wave surfing), a surfer is towed into the wave by a motorized water vehicle, such as a jetski, generally because standard paddling is often ineffective when trying to match a large wave's higher speed.