Lock washers are small, circular metal devices used to prevent nuts and bolts from loosening due to vibration or movement. They are designed with a split or a raised section that creates tension when compressed, helping to maintain a secure connection between fasteners. These washers come in various shapes, such as split lock washers and tooth lock washers, each serving a specific purpose. They are commonly used in construction, automotive, and machinery applications, ensuring that components remain tightly fastened over time.