Held off the ground by blasts of air, a hovercraft can skim over water or flat land. By this same virtue, it can ignore small obstacles or dangers that would stop a vehicle that makes contact with the ground.
Some hovercraft make use of a cushion of air trapped underneath by flexible fabric skirts that go around the vehicle. Others use high-efficiency ducted fans, and/or jets and ground effects (the design of the fuselage and faring trap and direct the air) to keep the vehicle airborne, albeit at a very low (1m or less) altitude. Hovercraft are generally very noisy due to the large amounts of air that must be moved at a high rate of speed both to keep it hovering and propel it forward. Hovercraft that use skirts are generally the most stable but the least maneuverable, while those that use ducted fans or jets are usually more nimble but kick up a lot of dust and debris in passing and must keep up a fairly high velocity for the ground effect to be most efficient.
Military hovercraft are typically called "Ground Effects Vehicles" or "GEVs".