A nest is a place of refuge to hold an animal's eggs or provide a place to live or raise offspring. They are usually made of some organic material such as twigs, grass, and leaves; or may simply be a depression in the ground, or a hole in a tree, rock or building. Human-made materials, such as string, plastic, cloth, hair or paper, may be used.
Generally each species has a distinctive style of nest. Nests can be found in many different habitats. They are built primarily by birds, but also by mammals (e.g. squirrels), fish, insects (e.g. wasps, termites and honey bees) and reptiles (e.g. snakes and turtles).
The urge to prepare an area for the building of a nest is referred to as the nesting instinct and may occur in both mammals and birds.