Drawing is the art of representing ideas through systematic lines on paper. There are two main types of drawings: artistic drawings which represent objects through an artist's imagination, and engineering drawings which represent engineering objects like buildings and machines. Engineering drawings can be created through freehand drawing, instrumental drawing using tools, or computer-aided drawing (CAD) using software like AutoCAD. AutoCAD is a commercial CAD software application first released in 1982 that is used to create, modify, and analyze 2D and 3D models.