Fri 27, Dec 2019 html
The answer to this fascinating interesting question is pretty simple:
You should only use .htm if your OS can't handle filename extensions longer than 3 characters:
All HTML documents should have filenames that end with the extension .html unless the files reside on a DOS system, in which case they should have the extension .htm.
"HTML Manual of Style" by Larry Aronson, 1994
DOS didn't support 4 character long filename extensions. That's why it was recommended to use .htm for DOS.
Back to top