A bathtub (AmE) or bath (BrE) is a plumbing fixture used for bathing. Most modern bathtubs are made of acrylic or fiberglass, but alternatives are available in the form of porcelain-coated steel or increasingly wood. Older western bathtubs are usually made of galvanized steel or porcelain over cast iron.
Until recently, most bathtubs were roughly rectangular in shape but with the advent of acrylic thermoformed baths, more and more shapes are becoming available. Bathtubs are typically white in colour although many other colours can be found.
Modern bathtubs encompass an overflow and waste and may have taps mounted on them. They may be built-in or free standing or sometimes sunken.
The issue of intended use is what separates a bathtub from a hot tub or other recreational bathing facilities. A bathtub is usually placed in a bathroom either as a stand-alone fixture or in conjunction with a shower. Any historical view of bathtubs should be aware of the 1917 bathtub hoax.
The process for enamelling cast iron bathtubs was invented by the Scottish-American David Dunbar Buick, who later went on to invent the OHV engine, and founded the Buick Motor Company.