A washer is a disk-shaped thin plate with a hole that distributes the load of the threaded equipment like nuts, screws, etc., It prevents the screws from damaging the thread when manual work is involved. It is used in every place that has a threaded interface and hence protects the surface from damages caused by human efforts. Washers are used in devices like filters to prevent mechanical vibrations and hence increase the lifespan of the filters and other devices.