A fence is a straight edge that is placed parallel to the direction of the cut saw

Saw

A saw is a tool that uses a hard blade or wire with an abrasive edge to cut through softer materials. The cutting edge of a saw is either a serrated blade or an abrasive...

blade. It is rigidly connected to the saw or table. The distance between the surface of the fence and the closest edge of the saw blade dictates the specified width of the cut. Material that is being cut is held tight against the fence in order to ensure that it is cut to the specified width.