A swimming Pool, swimming bath or simply pool is a structure designed to hold water to enable swimming or other leisure activities. Pools can be built into ground (inground pools) or built above ground (as a free standing construction or as part of a building or other large structure). Inground pools are commonly constructed from materials such as concrete, natural stone, metal, plastic, or fiber glass, and can be of a custom size and shape or built to a standardized size, the largest of which is the olympic-size swimming pool.
Many health clubs, fitness centers, and private clubs have pools used mostly for exercise or recreation. It is common for municipalities of every size to provide pools for public use. Many of these municipal pools are outdoor pools but indoor pools can also be found in buildings such as leisure centers. Hotels may have pools available for their guests to use at their own leisure. Pools as a feature in hotels are more common in tourist areas on near convention centers.
Education facilities such as high schools and universities some times have pools for physical education classes, recreation activities, leisure, and competitive atheletics such as swimming teams. Hot tubs and spas are pools filled with water that is heated and then used for relaxation or hydrotherapy. Specially designed swimming pools are also used for diving, water sports, and physical therapy as well as for training of life guards and astronauts. Swimming pools most commonly used chlorinated water or salt water and may be heated or unheated.