AutoCAD is a computer-aided design software that lets you design 2-D and 3-D drawings and models, replacing traditional pencil-and-paper drafting to create blueprints with easily altered electronic files. In the “AutoCAD 2009 and AutoCAD LT 2009 Bible,” Ellen Finkelstein writes that the software’s release in 1982 marked the first time a CAD program was designed for use on personal computers instead of mainframes.