Playas are among the most common of desert landforms, with more than 50,000 worldwide and with great variation in size and physical characteristics. They range from a hectare or less to hundreds of square kilometers, and they may support aircraft landings or be totally impassable to land vehicles. Because they possess distinctive physical attributes and are common elements of arid and semiarid landscapes, which occupy nearly 30% of the Earth's land surface, they have had significant effects on military history and operations for centuries. This significance is not apt to diminish.

The single most important determinant of playa-surface conditions is the combination of surface and ground-water hydrology. Playas with ground water that is sufficiently deep to preclude capillary rise favor hard surface crusts. Prolonged capillary or direct ground-water discharge in arid environments readily builds up evaporite mineral assemblages including halite, gypsum, and calcite. Changing hydrologic conditions resulting either naturally or from human activity, for example, ground-water extraction, can result in alteration of relief and surface hardness of playas over both short- and longer-time spans.

Military use by ground forces includes both expeditious and evasive maneuvering of ground vehicles. Air and spaceborne vehicles, including fixed and rotary wing craft and spacecraft, have used numerous playas in their natural state as landing platforms, and many other playas are readily available in remote, unpopulated areas of the globe. Future uses are apt to take advantage of the unique attributes of this arid-region feature—the flattest of all landforms.