I’ve been using Emacs for over 20 years and I still keep discovering (and rediscovering) comment-related commands and variables. You’d think that after two decades I’d have comments figured out, but it turns out there’s a surprising amount of depth hiding behind a few keybindings. What prompted this article was my recent work on neocaml, a tree-sitter based major mode for OCaml. OCaml uses (* ... *) block comments – no line comments at all – and that unusual syntax forced me to dig deeper into how Emacs handles comments internally. I learned more about comment variables in the past few months than in the previous 20 years combined.