If you bind a key to a keymap Emacs will display a useful prompt in the echo area. Quite handy for rarely used keymaps with only a few bindings.
This is (of course) well documented in the Emacs info manuals, but my discovery of it should be credited to u/oantolin on reddit.
Minor update: it is better to use
define-prefix-command as this
creates both a keymap and an interactive function. I've found that binding a
key to a variable, instead of an interactive function, is not widely
(define-prefix-command 'pkg-ops-map nil "Packages") (let ((map pkg-ops-map)) (define-key map "h" '("describe" . describe-package)) (define-key map "a" '("autoremove" . package-autoremove)) (define-key map "d" '("delete" . package-delete)) (define-key map "i" '("install" . package-install)) (define-key map "s" '("selected" . package-install-selected-packages)) (define-key map "r" '("refresh" . package-refresh-contents)) (define-key map "l" '("list" . list-packages))) (global-set-key (kbd "C-c p") 'pkg-ops-map)