VIM
* i - go to insert mode starting before the current cursor position
* a - go to insert mode starting after the current cursor position
* o - go to insert mode after adding a new blank line after the current one
* esc - This exits insert mode and brings you back to normal mode.
* :q! + enter - Quit and discard changes
* :wq + enter - Save changes and quit
* :w + enter - Save changes but stay in the editor
* :q - quit
* :x - write file, then quit
* u - undo last edit
* ctrl-r - redo
* / - search forward in the file
* ? - search backward in the file