A "loo" is a British term for a toilet or restroom. It is commonly used in informal settings and is understood by many English speakers around the world. The word is thought to have originated from the French phrase "gardez l'eau," which means "watch out for the water," a warning to those nearby when someone was using a toilet. In the UK, loos can be found in homes, public places, and businesses. They often include basic amenities such as a toilet, sink, and sometimes additional features like a mirror or hand dryer. Public loos are typically maintained by local authorities and may require a small fee for use.