Surfing is a surface water sport where a person (the surfer) moves along the face of a breaking ocean wave (the surf). Surfing also takes place on rivers, riding a standing wave.

Two major subdivisions within stand-up surfing are longboarding and shortboarding, reflecting differences in surfboard design including surfboard length, and riding style.

In tow-in surfing (most often, but not exclusively, associated with big wave surfing), a motorized water vehicle, such as a personal watercraft tows the surfer into the wave front, helping the surfer match a large wave's higher speed, a speed that is generally, but not exclusively a speed that a self-propelled surfer can not match.

Surfing-related sports such as paddleboarding and sea kayaking do not require waves, and other derivative sports such as kitesurfing and windsurfing rely primarily on wind for power, yet all of these platforms may also be used to ride waves.

Recently with the use of V-drive boats, wake surfing, riding the boat wake has emerged.