In this chapter, we were introduced to 3D. We saw the importance of the third coordinate, how to enter points in absolute or relative coordinates, and the application of point filters. We analyzed workspaces and how to control the AutoCAD environment. The importance of layers, transparency, and other properties were then explained. Auxiliary tools were then covered before we looked at how to use them to ease the 3D project. We then saw the application of those commands in 3D used daily and some that are particularly important, such as BOUNDARY. We also covered the linear 3D commands and the Thickness property. We concluded the chapter by covering good practices when modeling in 3D.