A steam vacuum cleaner combines steam cleaning (sanitizing with hot vapor) and vacuuming (removing dirt/dust) in one device, using high-temperature steam to deep clean and disinfect surfaces while simultaneously sucking up the loosened grime, often binding dust in a water filter, making it great for hard floors, upholstery, and deep sanitizing without harsh chemicals, though caution is needed on delicate materials like unsealed wood or painted surfaces.