Animal coloration is the general appearance of an animal resulting from the reflection or emission of light from its surfaces. Some animals are brightly coloured, while others are hard to see. In some species, such as the peacock, the male has strong patterns, conspicuous colours and is iridescent, while the female is far less visible.

There are several separate reasons why animals have evolved colours. Camouflage enables an animal to remain hidden from view. Signalling enables an animal to communicate information such as warning of its ability to defend itself (aposematism). Animals also use colour in advertising, signalling services such as cleaning to animals of other species; to signal sexual status to other members of the same species; and in mimicry, taking advantage of another species' warning coloration. Some animals use colour to divert attacks by startle (deimatic behaviour), surprising a predator e.g. with eyespots or other flashes of colour, and possibly by motion dazzle, confusing a predator's attack by moving a bold pattern (such as zebra stripes) rapidly. Some animals are coloured for physical protection, such as having pigments in the skin to protect against sunburn, while some frogs can lighten or darken their skin for temperature regulation. Finally, animals can be coloured incidentally. For example, blood is red because the haem pigment needed to carry oxygen is red. Animals coloured in these ways can have striking natural patterns.