Emacs: how to change from insert mode to overwrite mode

 How do I make Emacs “typeover” or “overwrite” instead of inserting?  i.e. change from insert mode to overwrite mode, like Esc + r in vim

Answer:
M-x overwrite-mode (a minor mode). This toggles overwrite-mode on and off, so exiting from overwrite-mode is as easy as another M-x overwrite-mode.

On some systems, Insert toggles overwrite-mode on and off.