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 also be used. generally each species has a distinctive style of nest. nests can be found in many different habitats.