The quick answer is AutoCAD has programming interfaces. With programming you can automate tasks involved in the drawing and editing process. This, however, is a surface response with a much more complex answer that I will now explain. AutoCAD is a vehicle to a different type of computer drawing that involves creating smart drawings.
Smart drawings are more than just lines, arcs and circles.
The key is to attach data of our own design to drawing objects so they can be retrieved at a later time by our applications. AutoCAD 2000 provides several ways that data can be attached directly to AutoCAD objects in the drawing. Let's look at each of them quickly and then explore the best solution for AutoCAD 2000 programmers. Extended data has been supported in AutoCAD for several releases and continues to provide a mechanism that works well. The only real problem with extended data is that it is somewhat cumbersome to manipulate.