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Four-wheel drive, 4WD, 4x4 ("four by four"), quattro, or AWD ("all wheel drive") is a four-wheeled vehicle with a drivetrain that allows all four wheels to receive torque from the engine simultaneously. While many people associate the term with off-road vehicles, powering all four wheels provides better control in normal road cars on many surfaces, and is an important part of rally racing.

In abbreviations such as 4x4, the first figure is the number of wheels; the second is the number of powered wheels. 4x2 means a four-wheel vehicle in which engine power is transmitted to only two wheels: the front two in front-wheel drive or the rear two in rear-wheel drive.

There is often confusion as to the difference between 4x4s and Sport Utility Vehicles. This leads to criticisms of 4x4 vehicles in the media that should actually be directed at Sport Utility Vehicles (see criticism of sport utility vehicles).