Lines starting with zero or more whitespace characters followed by ‘#’ and a whitespace are treated as comments and, as such, are not exported.
Likewise, regions surrounded by ‘#+BEGIN_COMMENT’ ... ‘#+END_COMMENT’ are not exported.
Finally, a ‘COMMENT’ keyword at the beginning of an entry, but after any other keyword or priority cookie, comments out the entire subtree. The command below helps changing the comment status of a headline.
Toggle the COMMENT keyword at the beginning of an entry.