Animals which blend with the color and texture of their environment are more likely to survive either as prey or as predators. Camouflaged prey have a greater chance of surviving by avoiding detection, whereas camouflaged predators can hunt more successfully if they can approach the prey without being seen.
The coloration of zebras makes them very conspicuous in the African plains, but the pattern of black and white stripes makes it very hard for predators to distinguish one individual in the middle of the herd. Do you see eight or nine zebras?