Drafting is used as a medium of communication between designers, clients, architects and builders. There are four common terms used in drafting: drawing, freehand drawing/sketching, mechanical drawing, and orthographic projection. Mechanical drawing uses drawing instruments and orthographic projection to describe object shapes completely and exactly. Drafting instruments include a T-square for horizontal lines, triangles for vertical lines, a divider for equal distances, and a French curve for curved lines. Lettering guidelines like cap, waist, base and drop lines are used for consistency in letter height and placement.