Member Avatar for Cup of Squirrel

Ok, this sounds very stupid but I have downloaded several pre-made templates and have found that most of them use the file extension .htm

I'm also worried some browsers may not support or display .htm properly :/

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  • Latest Post Latest Post by Static-FMX-Prog

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As asked and as and already pointed out, the two extensions are just naming conventions for HTML files. Browsers render whatever the server serves based on the HTTP Content-Type (text/html), not the filename itself — see MDN on MIME types. Background on filename limits and conventions is covered on Wikipedia.

Practical points worth noting years later:

  • Filesystems differ: Windows hosting is typically case-insensitive, while Linux/Unix hosts are case-sensitive. page.HTM, page.htm and page.html can be distinct on many servers.
  • Default documents: servers often look for index.html or index.htm (configurable; see Apache DirectoryIndex), so consistency avoids surprises.
  • Changing extensions on a live site breaks links unless redirects are added, so prefer consistency or use redirects when migrating.

Quick migration/redirect examples (adjust to site structure and test before deploying):

# Apache (in .htaccess)
RedirectMatch 301 ^/(.*)\.htm$ /$1.html
# Nginx
rewrite ^/(.*)\.htm$ /$1.html permanent;
# Bulk rename on Unix
for f in *.htm; do mv "$f" "${f%.htm}.html"; done

Recommendation: pick one convention (many teams prefer .html for clarity), keep file names consistent, and, when changing existing URLs, add 301 redirects to preserve links and SEO. Modern frameworks and static-site setups often serve extensionless URLs or rely on index.html, so extension choice matters less there but consistency still matters.

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Member Avatar for DaveSW

They both mean a html file.
the reason that there is two, is that seriously old computers only supported 3 letters in the file extension. Now that is no longer a problem, but people just haven't moved on.
So just use whatever is easiest for you - some editors make .htm files by default, some .html. Just don't waste your time going round changing them all...

Member Avatar for Cup of Squirrel

Ok, thanks for the help :D

Member Avatar for Static-FMX-Prog

Its the same pal.. The reason there was a .htm is because a little while back you couldnt have 4 letter extentions.. Exactly the same.. no difference.. but, you can still use .htm if you chose.

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