CAD is an acronym that stands for Computer Aided Design, the use of computer technology to aid in design and drafting of a part or a product, and often entire buildings as well. Computer aided design comprises both visual and symbol based methods of communication particular to a specific technical field, such as engineering drawing or technical drawing. Computer aided design can be done both in two dimensional and three dimensional forms. Designers can buy AutoCAD software packages ranging from 2d vector-based drafting systems to 3d surface modelers and solid modelers. When looking to buy AutoCAD software, modern computer aided design packages can be found that allow for three dimensional rotations, which is extremely useful. Sometimes computer aided design is referred to as CADD, which stands for computer aided design and drafting.