Military camouflage is the use of camouflage by an armed force to protect personnel and equipment from observation by enemy forces. In practice, this means applying colour and materials to military equipment of all kinds, including vehicles, ships, aircraft, gun positions and battledress, either to conceal it from observation (crypsis), or to make it appear as something else (mimicry). The French slang word camouflage came into common English usage during World War I when the concept of visual deception developed into an essential part of modern military tactics. In that war, long-range artillery and observation from the air combined to expand the field of fire, and camouflage was widely used to decrease the danger of being targeted or to enable surprise. As such, military camouflage is a form of militarydeception.
Camouflage was first practiced in simple form in the mid 18th century by jager- or rifle units. Their tasks required them to be inconspicuous, and they were issued green and later other drab colour uniforms. With the advent of longer range and more accurate weapons, especially the repeating rifle, camouflage was adopted for the uniforms of all armies, spreading to most forms of military equipment including ships and aircraft. Many modern camouflage textiles address visibility not only to visible light but also near infrared, for concealment from night vision devices. Camouflage is not only visual; heat, sound, magnetism and even smell can be used to target weapons, and may be intentionally concealed. Some forms of camouflage have elements of scale invariance, designed to disrupt outlines at different distances, typically digital camouflage patterns made of pixels. Camouflage patterns also have cultural functions such as political identification.
Camouflage for equipment and positions was extensively developed for military use by the French in 1915, soon followed by other World War I armies. In both world wars, artists were recruited as camouflage officers. Ship camouflage developed via conspicuous dazzle camouflage schemes during WWI, but since the development of rader, ship camouflage has received less attention. Aircraft, especially in World War II, were often countershaded: painted with different schemes above and below, to camouflage them against the ground and sky respectively.
Military camouflage patterns have been popular in fashion and art from as early as 1915. These days camouflage patterns can be seen everywhere (non-military) in fashion apparels, backpacks, mobile phone casings etc.