In ethology, territory is the area that a species of animal consistently defends against related animals. Sometimes it means areas defended against animals of other species. Animals that defend territories in this way are referred to as territorial.

Territoriality is not shown by most species. More commonly, a group of animals has an area that they use but do not necessarily defend. This is called their home range. The home ranges of different groups of animals often overlap, and in the overlap areas, the groups tend to avoid each other.

Many animals use vocalisations to advertise their territory. These are short-term signals given only when the animal is present. The sound can travel long distances and through various habitats. Examples include birds,^[1] frogs and canids.

Scent markings are used by many mammals. Some have special scent glands; others squirt urine on key places. Domestic cats have graded ritualized aggression. This starts off with vocalizations and sometimes mounts to direct attack.

Territories may be held by an individual,^[2] a mated or unmated pair, or a group, and it may vary at different times of the year.