4 Wheel Drive/SUVs: 4x4, four wheels, two wheels

Question
what does 4x4 stand for please?

Answer
4x4 means that the vehicle has the ability to drive(deliver power) to all four wheels.  Normally the vehicle only drives two wheels but can be switched to four wheel drive by the driver.  Most 4 wheel drives also have a low range where you need a lot of power rather than speed.  Do not confuse 4x4 with AWD which is all wheel drive where all four wheels are powered all the time.  There are many variations of both but this is the basic answer.  Thanks for the interesting question.  Best of luck, Bud