(Date: 26 June 2024)
which-key is a package which provides the minor-mode which-key-mode which helps with discovery of key bindings.
Enable it with (which-key-mode) in your init file.
Upon entering an incomplete prefix command, such as C-x, it pops up the available commands under this prefix.
which-key is useful as a reminder of key bindings, as well as a way to explore unknown commands.
It was previously distributed on ELPA. After multiple patches to adapt it to Emacs core, it has also been merged into Emacs master. See https://git.savannah.gnu.org/cgit/emacs.git/commit/?id=fa4203300fde6820a017bf1089652fb95759d68c
which-key is expected to be released as part of Emacs 30.
Going forward it will now be developed as part of Emacs. (The previous repo has been archived.)
It will also continue in ELPA, as a :core package.