A scooter is a two-wheeled vehicle with a step-through frame.
The classic scooter design features a step-through frame and a flat floorboard for the rider's feet. This design is possible because the scooter engine and drive system, transferring power to the rear wheel, is either attached to the rear axle or under the seat. In contrast to a frame mounted motorcycle engine, this front-hinged arrangement allows the engine to swing vertically in conjunction with the motion of the rear wheel. Older Vespas, most vintage scooters, and some newer retro models have axle mounted engines with a manual transmission with the gear shift and clutch controls built into the left handlebar.
Scooters trace their ancestry back to France with the Auto-Fauteuil mark in 1902, 1903 in the USA, where Cushman and Salsbury created some of the first motorized two wheelers with the traits that have come to embody scooters. Salsbury produced the first automatic scooter with a Continuously Variable Transmission (CVT). Cushman's light, compact, and rugged scooters were used by the United States military as ground vehicles for paratroopers during World War II. The Vespa, originally manufactured by Piaggio in post-WWII Italy, quickly popularized motor scooters in places where inexpensive transportation was in dire need. Constructed using aircraft design and materials and eliminating belt drive by mounting the engine on the axle it redefined the vehicle type for 35 years. Despite Vespa's dominance of the scooter market, they were not without competition. Lambretta offered models that rivaled those in the Vespa product line, as did many well-known Italian marques including Iso and MV Agusta. Germany had many, with examples from Maico, Durkopp, Heinkel, Goggo and many others. Poland and Czechoslovakia (under Russian occupation) both produced successful scooters, as did most of the European nations.