A toilet is a plumbing fixture primarily intended for the disposal of human excreta: urine and fecal matter. Additionally, vomit and menstrual waste are sometimes disposed of in toilets in some societies. The word toilet describes the fixture and, especially in British English, the room containing the fixture. In American English, the latter is euphemistically called a restroom or bathroom. The latter term often describes a room that also contains a bath tub. A room with only a toilet and a sink is sometimes called a half-bathroom, a half bath, or a powder room.

There are two basic types of modern toilets: the dry toilet and the wet (flush) toilet, the latter being the most commonly known and producer of blackwater. The dry toilet needs no plumbing for water input or evacuation, but is often coupled with a ventilation system.

Prior to the introduction of modern flush toilets, most human waste disposal took place outdoors in outhouses or latrines. However, the ancient cities of the Indus Valley Civilization, e.g., Harappa and Mohenjo-daro, which are located in present day India and Pakistan, had flush toilets attached to a sophisticated sewage system—and other forms of toilets were used both in the time of the Romans and Egyptians as well. Although a precursor to the modern flush toilet system was designed in 1596 by John Harington, the toilet did not enter into widespread use until the late nineteenth century, when it was adopted in English upper class residences.