Emacs Lisp: Comment
A comment is text that is ignored by emacs lisp. Usually used to annotate the code, or documentation, or for copyright info.
Comment syntax starts with one semicolon to end of line. There is no other syntax.
;; this is a comment (+ 1 2) ; result is 3 ;; by emacs convention, comment on a line by itself starts with 2 semicolons ;;; HEADER COMMENT ;; by emacs convention, comment starting with 3 semicolons is a header, e.g. section title