Flat Washers: A standard washer with a central hole, used to spread the load on surfaces fastened with screwed fixings.
Split Washers: A washer with a split section in the diameter that helps provide resistance to unwanted loosening due to vibration.
Wave / Crinkle Washers: A variant of washer that has a wave effect across the diameter of the surface providing greater tension between the surface and the screwed fastener.
Locking / Shakeproof Washers: A washer with grooves, teeth, or ridges that grip firmly in to the surfaces to provide a strong resistance against unwanted turning.
Finishing / Conical Washers: Provide a more finished appearance when used with the appropriate fasteners by providing a smooth finish to surfaces when using fasteners that would otherwise have the head visible. While still providing extra torsion on the surface.