Mercury is the only metal that is liquid at standard room temperature.
Its chemical symbol is Hg, derived from the Latin name hydrargyrum, meaning “liquid silver.” Mercury melts at about −38.83 °C, so it remains liquid under ordinary indoor conditions while most metals are solid.
The element was historically used in thermometers, barometers, switches, and some industrial processes. Many older thermometers contained mercury because its volume changes predictably with temperature and it is visible inside a narrow glass tube.
Gallium and cesium can also melt near room temperature, but they are normally solid at typical indoor temperatures. Bromine is liquid at room temperature too, but it is a halogen and therefore not a metal. Mercury is toxic, so many modern devices use safer substitutes.