A heated pool is a swimming pool that has its water temperature maintained at an elevated level, usually through the use of some form of artificial heat source such as electric or gas heaters. This allows for year-round enjoyment of the pool and makes it more comfortable to swim in during colder months when natural outdoor temperatures might not be warm enough. The term "heated pool" is generally used to refer specifically to pools that have been intentionally warmed up, as opposed to unheated or indoor pools which are always maintained at a higher temperature due to their environment.