Two-wheel drive is a type of automobile layout in which two wheels are connected to the engine and used to propel the vehicle forward. The other two wheels spin freely but do not actively drive the vehicle forward.
A two-wheel drive vehicle can be front-wheel drive or rear-wheel drive; on a front-wheel drive car, the wheels at the front of the vehicle are used to propel the car forward, while on a rear-wheel drive car, the rear wheels are used to move the car forward.
Each design has distinct advantages and disadvantages depending on how the vehicle is intended to be used.
Two-wheel drive vehicles with the drive wheels in the front, tend to have good traction because the weight of the engine keeps the drive wheels in place during slick conditions, but steering can be affected by this weight.
Rear-wheel drive cars may not have such good traction in slick conditions, but these two-wheel drive vehicles will tend to have better handling in most driving conditions.
Some four-wheel drive vehicles spend the most time in a two-wheel drive configuration; the front wheels only drive the vehicle when it is switched into a four-wheel drive configuration.