CAD is mainly used for detailed engineering of 3D models and/or 2D drawings of physical components, but it is also used throughout the engineering process from conceptual design and layout of products, through strength and dynamic analysis of assemblies to definition of manufacturing methods of components.
We use SolidWorks which is a 3D mechanical CAD program to design 3D solid modeling, so you can see what you are going to get, well before it is manufactured.
