A skateboard is a four wheeled platform used for the activity of skateboarding. It is propelled by pushing with one foot while the other remains on the board, or by pumping in structures such as a half-pipe. A skateboard can also be used by simply standing on the deck while on a downward slope and allowing gravity to propel the board and rider. That having been said, there is no governing body which declares any regulations on what constitutes a skateboard or the parts from which it is assembled. For example, longboards are a type of skateboard with a longer wheelbase and larger and softer wheels. Thus, the definition of a skateboard can vary in shape, size, overall appearance, as well as in aptitude for performance.

There is no definitive origin or inventor of the skateboard. One proposed origin is that skateboards arose in the 1930s and 1940s, when children would participate in soapbox races, using soap-boxes attached to wooden planks on rollerskate wheels. When the soap-box became detached from the plank, children would ride these primitive "skateboards". Another suggests that the skateboard was created directly from the adaptation of a single roller skate taken apart and nailed to a 2x4, without the soapbox at all and that it was often surfers looking to recreate the feel of surfing on the land when the surf was flat.

Retail skateboards were first marketed in 1958 by Bill and Mark Richards of Dana Point, California. They attached roller skate wheels from the Chicago Roller Skate Company to a plank of wood and sold them in their Val Surf Shops.

The skateboard has evolved since the first mass produced models in the 1960s. Boards in the past were often made in the shape of a surfboard, with no concavity and constructed of solid wood, plastic, even metal. The wheels were usually made of a clay composite, or steel and the trucks (axles) were less sturdy and initially of a 'single-action' design compared to today's 'double-action'.