In past I had to learn myself GIT and I always tought that documentation to explain GIT was just not clear.
So I wrote small charts to help everybody to understand how to use GIT and understand what are differences between stash area, workspace, local database, remote database, index, and stage area just by reading this chart. I really think such chart should be the default chart to use to explain GIT.

With 2 charts, all areas and rules of GIT command using them are represented...

List of GIT space areas and effect of commands

List of file status