Computer-aided design, or CAD, is the use of a computer to display designs, accept any changes to them and calculate and display the results.

CAD has many different applications, which include:-

• Designing new cars;
• Bridge and building design and testing;
• Printed circuit board (PCB) design;
• Designing new aircraft;
• Designing fitted kitchens.

Making changes to a design requires a large number of complex calculations. These need to be performed as quickly as possible so that their effect can be viewed straight away.

A powerful processor is required for this. A CAD system also needs a high-resolution monitor so that clear close-up detail can be seen on the screen.

Input to CAD systems is normally given using a mouse and keyboard but other input devices such as graphic tablets and scanners are also used.

Output from a CAD system is produced using a high quality printer such as a laser printer or a plotter.

The advantages of CAD systems are:-

• Changes to a design can be made quickly and their effects seen straight away;
• Designs can be viewed from any angle without being re-drawn;
• Designs can be tested without the need to build expensive models or prototypes;
• Drawings can be stored on disk and re-used at any time;
• Designs can be instantly sent anywhere in the world using electronic communications;
• Designs can be used directly in computer aided manufacturing processes.