It is important to adapt to one's environment for animals survive. Camouflage is used to blend into their surrounding by plants and animals. Most animals use camouflage to hide themselves from others. Larger animals use camouflage when sneaking up on prey. Zebras,rabbits and many reptiles use camouflage in order not to prey.
Mammals and birds cannot change the color of their feathers or fur. But some reptiles and fish can change their pigmentation. The chameleon can change the color of the body to match around. When a potential attacker approachs,the chameleon change the color of the skin to match the color of the standing. This is one of the chameleon's physiology. Most animals have only one color, but the Arctic fox change color of hair according to the season. This is actually a chemical reaction.
Camouflage is also hiding the color of the background. In this case,animals does not change the color of them. For example,a green grasshopper ride on a green leaf.
Countershading is a technique of camouflage. Animals has two opposite shadeson their body. For example,the dorsal area of shark is dark blue,but its underbelly is lighter whitish. All the techniques of camouflage are important to blending into the surroundings and surviving.