A mechanical seal is a device used in various industrial applications to prevent the leakage of fluid (liquid or gas) between two closely spaced surfaces, typically a rotating shaft and a stationary housing. It is an essential component in pumps, compressors, mixers, and other equipment that handle fluids. Mechanical seals are designed to maintain a reliable seal under different operating conditions, including high pressure, temperature variations, and abrasive or corrosive fluids.