This chapter explores how to interpret diagram applications specifying the maximum material condition and the least material condition. It shows how to insert tolerances to drawings. Geometric tolerancing is the dimensioning and tolerancing of individual features of parts in which the permissible variations relate to characteristic form, profile, orientation, run-out, or the relationship between features. There are three systems for applying dimensions and tolerances to a drawing: baseline, chain and direct. Straightness is a condition where an element of a surface, or an axis, is a straight line. A straightness tolerance is applied in the view where the elements to be controlled are represented by a straight line. A circularity tolerance is used to limit the amount of variation in the roundness of a surface of revolution. It is measured at individual cross sections along the length of the object.