What is washer ?
Washer is a thin plate (typically disk-shaped, but sometimes square) with a hole (typically in the middle) that is normally used to distribute the load of a threaded fastener, such as a bolt or nut
Flat thin ring or a perforated plate used in joints or assemblies to ensure tightness, prevent leakage, or relieve friction
Purpose of the washers are :
1. Load distribution
2. Spacing
3. Vibration absorption
4. Prevent leakage
5. Relieving friction
6. Ensure tightness