When a car makes a left turn, the interior-facing wheels (on the left side) naturally turn slower than the exterior-facing wheels (on the right side) because the exterior-facing wheels have to travel farther to get the car around the corner. For this reason, the wheels of a car need to be able to revolve independently and at varying speeds to prevent slipping, and to keep the car moving with power around corners.
A car’s differential is a mechanical set of simple planetary gears that allows wheels to spin at independent speeds, and to be independently powered by the engine through the car’s drivetrain.
