A lock washer is a type of fastener designed to prevent loosening under vibration and torque. Typically made of metal, it has a split or irregular shape that creates tension when compressed between a nut and a surface. The unique design allows it to grip the surfaces firmly, providing resistance to rotational movement. Commonly used in machinery, automotive, and construction applications, lock washers enhance the reliability of connections. They come in various forms, such as split, toothed, and wave washers, each suited for specific conditions and load requirements. Proper installation is crucial for optimal effectiveness.