A draughtsman or draftsman is a person who prepares technical drawings and plans under the direction of an architect or engineer. In the past, draftsmen used drawing boards and pencils, T-squares, set squares, inking pens, compasses, protractors and other drafting devices to prepare a drawing by hand. With the advent of computers and Computer Aided Design and Drafting (CADD) systems, the manual techniques have been replaced by computer drawings. Consequently, some draftsmen would have upgraded their skills and may now be CADD operators. With CADD systems, draftsmen can create and store drawings electronically so that they can be viewed, printed, or programmed directly into automated manufacturing systems. CADD systems also permit drafters to quickly prepare variations of a design. Although drafters use CADD extensively, it is only a tool. They still need knowledge of traditional drafting techniques, in addition to CADD skills. Despite the nearly universal use of CADD systems, manual drafting and sketching are used in certain applications. Drafters’ drawings provide visual guidelines and show how to construct a product or structure. Drawings include technical details and specify dimensions, materials, and procedures. Drafters fill in technical details using drawings, rough sketches, specifications, and calculations made by engineers, surveyors, architects, or scientists. For example, drafters use their knowledge of standardized building techniques to draw in the details of a structure. Some use their understanding of engineering and manufacturing theory and standards to draw the parts of a machine; they determine design elements, such as the numbers and kinds of fasteners needed to assemble the machine. Drafters use technical handbooks, tables, calculators, and computers to complete their work.