A habitat is the natural home or environment of a plant, animal, or other organism. It provides the organisms that live there with food, water, shelter, and space to survive. Habitats consist of both biotic and abiotic factors. Biotic factors are living things, while abiotic factors are nonliving things. Examples of habitats include forests, grasslands, deserts, freshwater, marine water, and brackish water. Habitats may be classified geographically into polar, temperate, subtropical, or tropical. In parasitology, a habitat is a location or an environment where the parasite is most likely to be found.