Underfloor heating is a type of heating system where hot water (or sometimes electricity) is used to warm up the floors in a room. Instead of having a radiator, heat comes up through the floors, warming them up. This heat then makes the room feel warm and cozy. Underfloor heating is usually installed below the floor at the beginning of building a home or room, and can be used as the main heating system or as a way to supplement other heating systems (like radiators).