An all-wheel drive vehicle (AWD vehicle) is one with a powertrain capable of providing power to all its wheels, whether full-time or on-demand. The most common forms of all-wheel drive are: 4×4 (also, four-wheel drive and 4WD)Reflecting two axles with both wheels on each capable of being powered.6×6 (also, six-wheel drive and 6WD)Reflecting three axles with both wheels on each capable of being powered.8×8 (also, eight-wheel drive and 8WD)Reflecting four axles with both wheels on each capable of being powered. Vehicles may be either part-time all-wheel drive or full-time: On-demand (also, part-time)One axle is permanently connected to the drive, the other is being connected as neededFull-time (also, permanent)All axles are permanently connected, with or without a differential.IndependentThe wheels are driven, but not dependent on a central mechanical power coupling.