Learning the vi Editor/vile
Vile - vi like Emacs
vile is a vi clone which doesn't claim to be a vi clone. The idea behind vile is to have an editor which works similar to vi but provides features for editing multiple files in multiple window-areas like emacs. In fact, vile development started by using MicroEMACS as the base, and not a vi clone, and also not full blown Emacs. MicroEMACS is an emacs-like editor (MicroEMACS's author didn't like full-blown emacs, and the vile authors didn't like (Micro)EMACS mode-less way of working). So vile was developed.
vile provides the most common vi commands (as used by their authors), but not all vi commands. The implemented commands are supposed to work more or less like the original vi commands. The window management and buffer management came from MicroEMACS.
Much work has gone into the vile documentation after the first versions were almost undocumented. It is recommended to consult the documentation to find out the differences and extensions of vile, compared to vi.