Computer aided design is not restricted to drawings of a product, it in fact refers to any use of computer software that supports a design process.
Commonly used for circuitry design, CAD software might use system blocks to identify which components are needed. It can also help to generate the design by calculating which components are required, as well as laying out a circuit diagram.
A common mistake is to believe that computer-aided design (CAD) refers only to drawings of a product when in reality CAD refers to any use of computer software that supports the design process.
An advantage of CAD software is that different design ideas can be changed quickly and easily. The circuit can be built and tested virtually to make sure that it will work. This helps to reduce the cost of buying parts and modifying prototypes.