A 4WD (four-wheel drive) system is a type of vehicle drivetrain that enables all four of its wheels to receive power from its engine simultaneously. This allows the vehicle to have enhanced traction and stability, which can be especially beneficial when driving on uneven or slippery surfaces. The main difference between 4WD and AWD (all-wheel drive) is that 4WD is only activated when needed, while AWD is active all the time.

In a 4WD system, the engine output is split between the front and rear axles, so that the engine is always driving all four wheels. When more power is needed, the driver can activate the 4WD system, which will transfer more power to the rear wheels, giving the vehicle better traction and stability. This is especially useful when driving on slippery surfaces such as snow, mud, or sand. On the other hand, AWD is always active, and the power is distributed to all four wheels at all times. AWD systems can also be used in conjunction with stability control systems, which can help the vehicle maintain its grip on the road and prevent it from skidding or sliding.