The term 'scooter' applies to two different kinds of vehicles. One is a small vehicle that is intended to be ridden while standing up and consists of a long footboard with small wheels at either end and an upright steering handle at the front. The other is a type of small motorcycle, sometimes called a motor scooter.

Motor scooters typically have smaller wheels than other motorcycles, step-through frames, and engines placed low and close to the rear wheels. Engine sizes traditionally have ranged from just under 50cc (mopeds) to around 250cc. Motor scooters can have engines much larger than this, however, and may reach speeds in excess of 100 miles per hour.

Most gas motor scooters are designed to be relatively easy to learn to ride, although parents should be aware that the most popular form of gas scooter sold in the US today, the 'pocket bike,' requires a great deal of skill to ride safely. The small size of pocket bikes makes them appealing to young people, but these are really small-competition motorcycles, rather than street-legal motor scooters. Enthusiasts appreciate pocket bikes for their impressive speed-to-size ratio, their fast acceleration, and racing performance.

Important brands of motor scooters in the US are Vespa (made by Piaggio), Honda, and Yamaha. Vespa is associated with classic styling and produced its first motor scooter in the 1940s. Vintage scooter enthusiasts also favor the Lambretta brand, originally from Italy. Aprilia is another European brand gaining a foothold in the US market.

Since the 1980s, Honda and Yamaha have been important players in the market for modern scooters. Modern scooters usually have automatic shift transmissions, plastic body panels, and a more futuristic design style than classic scooters. Another type of motor scooter is the mini-chopper, a motor scooter designed to look like a small Harley-Davidson motorcycle, or 'chopper.'