Wow! This post from Mickey is something I had no idea about. In Emacs 28, there’s a builtin cheat sheet for Elisp functions. You call shortdoc-display-group and are presented with a list of categories or “groups”. When you choose a group, you get a cheat sheet that covers all the Elisp functions in that category.
It’s easier to try than to describe. Just call shortdoc-display-group, pick a group, and take a look at the resulting cheat sheet. To the first order, that’s all there is to it but, of course, it’s Emacs so there is a bit more. You can extend the cheat sheets. See Mickey’s post or the documentation for more information on that.
If you’re an Elisp programmers this is a boon. There are a lot of Elisp functions and no one I know has memorized them all. You can, of course, look them up in the manual but it’s harder to locate the function you need and not nearly as convenient. If you do a lot of Elisp programming it’s probably worthwhile to bind a key sequence or alias to shortdoc-display-group. One could, for example, set the alias cheat to shortdoc-display-group. That’s easy to remember and a quick way of invoking the command.
This is a really worthwhile (and more or less hidden) addition to Emacs 28. I’m really glad to have it.