Geometric tolerances are generally called geometric tolerances including shape tolerances and position tolerances. Any part is composed of points, lines, and areas. These points, lines, and areas are called elements. After machining, the actual elements of the parts always have errors relative to the ideal elements, including shape errors and position errors. Such errors affect the function of mechanical products, and corresponding tolerances should be specified in the design and marked on the drawings according to the prescribed standard symbols.