A dicycle is a vehicle with two parallel wheels, side by side, unlike single-track vehicles such as motorcycles and bicycles, which have two wheels inline. Originally used to refer to devices with large wheels and pedals, the term is now used in relation to powered self-balancing scooters with smaller wheels and no pedals such as the Segway PT and the self-balancing hoverboard.

A personal transporter is any of a class of compact, mostly recent, motorised micromobility vehicle for transporting an individual at speeds that do not normally exceed 25 km/h (16 mph). They include electric skateboards, kick scooters, self-balancing unicycles and Segways, as well as gasoline-fueled motorised scooters or skateboards, typically using two-stroke engines of less than 49 cc (3.0 cu in) displacement. Many newer versions use recent advances in vehicle battery and motor-control technologies. They are growing in popularity, and legislators are in the process of determining how these devices should be classified, regulated and accommodated during a period of rapid innovation.