A primitive solid is a ‘building block' that you can use to work with in 3D. Rather than extruding or revolving an object, AutoCAD has some basic 3D shape commands at your disposal. From these basic primitives, you can start building your 3D models. In many cases, you get the same result from drawing circles and rectangles and then extruding them, but doing it one command is generally faster. Using these with Boolean operations can be a very effective way of drawing in 3D.
The aim of these videos is to give those who are new to Autocad a clear understanding of viewports and through the process will explain the modelspace and paperspace functionality. For those struggling with particular areas of autocad we will endeavor to post more videos covering topics where there is strong demand. Hope these videos help.