A lock washer is a type of fastener used to prevent nuts and bolts from loosening due to vibration or movement. It is typically made of metal and has a split or curved design that creates tension when compressed. This tension helps maintain a secure connection between components. Lock washers come in various shapes, such as split lock washers and tooth lock washers, each serving specific applications. They are commonly used in machinery, automotive, and construction settings to enhance the reliability of assembled parts. Proper installation of lock washers is essential for optimal performance.