Technical drawings are created using a variety of instruments, ranging from traditional tools, such as pencils, compass, and triangles, to the computer. Drawing tools are used to make accurate and legible drawings and models. Traditional drawing instruments are still important, especially for sketching; today, however, the computer can be used for most drawing and modeling requirements. This chapter is an introduction to computer-aided design/ drafting (CAD) systems, including the related hardware, software, and peripheral devices, and the traditional equipment normally used by engineers and technologists to create technical drawings and models.