Camouflage is an adaptation of appearance. It is an attempt to avoid observation and prevent detection by enemies. The principle is simple: hide yourself by modifying your appearance that it matches the environment. People have been using camouflage in some form or another from the beginning of human civilization.
Camouflage has a great importance in warfare. Warplane, warships, tanks, soldiers use human-made forms of camouflage to adapt the appearance to the expectation of potential enemies, which expect to see the original landscape. They try to disappear on the battlefield by using a suitable disguise which matches the background perfectly. Military clothing such as combat uniforms mirror the environment of the battle: people fighting in the desert will wear a desert camouflage pattern, people fighting in the jungle will wear a woodland camouflage pattern.
Caterpillars, frogs, snakes, reptiles and many other animals try to avoid observation by using camouflage, too. They only use natural forms of camouflage: stripes, spots and patterns in various colors. They deceive potential predators by sophisticated camouflage techniques which show them what they expect to see.