A motorboat generally speaking is a vessel other than a sailboat or personal watercraft, propelled by an internal combustion engine driving a jet or a propeller. However, the International Regulations for Preventing Collisions at Sea defines it as any vessel propelled by machinery. A speedboat is a small motorboat designed to move quickly, used in races, for pulling water skiers, as patrol boats, and as fast-moving armed attack vessels by the military.

There are three popular variations of powerplants: inboard, inboard/outboard, and outboard.
If the engine is installed within the boat, it's called a powerplant; if it's a removable module attached to the boat, it's commonly known as an outboard motor.

An outboard motor is installed on the rear of a boat and contains the internal combustion engine, the gear reduction, and the propeller.

An inboard/outboard contains a hybrid of a powerplant and an outboard, where the internal combustion engine is contained inboard and the gear reduction and propeller are outside.

A purely inboard boat contains everything except a shaft and a propeller inside the vessel. There are two configurations of an inboard, v-drive and direct drive. A direct drive has the powerplant mounted near the middle of the boat with the propeller shaft straight out the back, where a v-drive has the powerplant mounted in the back of the boat facing backwards having the shaft go towards the front of the boat than making a 'V' towards the rear.

Motorboats vary greatly in size and configuration, from the 4-meter, open Boston Whaler type to the luxury mega-yachts capable of crossing an ocean.

Motorboats are also popular with modern pirates, who value it's speed and small size. Some pirates have been know to mount machine guns on their, boats, and attack from them with assault rifles and rocket-propelled grenades.