.htm .php .shtml .vm etc, what do they mean?

[Briggs]

I am really curious about this, actually.

What do they mean? And how to you use those weird ones like .vm or .asp ?

[codeexploiter]

For a stranger these file extensions may look alien but for a person who know some of the technologies can identify the type of the files by looking at their extension.

If you consider file extension .htm or .html a person who knows Hyper Text Markup Language (HTML) can understand that the file is a web page which can be viewed using a web browser.

If you consider .php and .asp both of them are server-side tools used in web development. ASP is the product from Microsoft and PHP which is an open source tool. So a developer can identify which technology used in a site just by looking at their file extensions.

VM is a file extension associated with Geoworks Virtual Memory files

Mostly standard tools tries to use a matching and more identifiable name as its file extensions.

[djr33]

The "weird ones" are rare because they serve a less common purpose.

The ending of any file determines it's type. This is not an actual determination of use or content but just a name. If you call a file by the wrong type it is still the same data and can still be read as such, but many applications, web servers, and even users will not treat it like that only because of expectation.

This ending is typically three letters because of old standards of 8.3 (8 character name . 3 character extension, which is why you'll see .ext a lot as a generic extension in examples), but now there are some that are 4 and a few that are 2 (though these might have existed then-- I'm not sure). The 4 character extensions may also have 3 character aliases, which creates some overlap such as .htm and .html which are exactly the same.

.htm[l] = hypertext markup [language]
This is for any general sort of webpage which can contain html, javascript and css, plus embed media and a couple other things, but through the html code, not that language in the source.

.php is hypertext pre-processor (reversed the letters for some unknown reason). It is a server programming language that allows interaction with databases, the server, etc, and outputs pure html-- a .htm page renamed .php will function identically except that it will also parse and php code first [into html, that is, if the server has a php parser installed].

.asp is the microsoft brand version of php-- php is open source, and more widely supported by this community.

.shtml is either secure, super, or server-side html-- I don't know, or really care. You'd use that for adding special code to your html like doing something on the server, etc. You'd know if you'd need to use it, anyway.

I don't know what .vm is-- it sounds vaguely familiar, but I've never used it or wanted to use it.

As for how you can use one of the weird ones, well, you'd have to properly use it for it's purpose, and you can't just randomly any extension as that dictates what file then what to do with it. You could use some sort of complex rewriting the URL on your server to give another page, but that's not worth it and would be confusing.

[Twey]

now there are some that are 4 and a few that are 2 (though these might have existed then-- I'm not sure).

The twos might have, but the fours didn't, or weren't very common -- the reason for the 8.3 "standard" (and all the cruft left over from that, like .htm) is that DOS didn't support any filenames that didn't fit into 8.3. UNIX supported longer filenames, though, so it could be that larger extensions were used there. In *nix today, extensions are a lot more flexible: .a, .o, .so, .txt, .conf, and .config are all fairly common, and extensions for text files are considered unnecessary and thus arbitrary, leading to README.install, &c.

[djr33]

My phrasing was vague-- I was just referring to the two character extensions. 4 were indeed too long.

[jscheuer1]

.htm - hyper teenage monsters
.php - popular holding patterns
.shtml - 'by gosh!' Mel
.vm - very maddening

[Jas]

.php is hypertext pre-processor (reversed the letters for some unknown reason).

Actually, it stands for PHP Hypertext Pre-Processor. The first letter is the acronym (known as a recursive acronym). Why they named PHP that, I don't know. I guess HP was taken (Hewlett Packard), .

[Briggs]

.htm - hyper teenage monsters
.php - popular holding patterns
.shtml - 'by gosh!' Mel
.vm - very maddening

Thanks for the responses!

[djr33]

Actually, it stands for PHP Hypertext Pre-Processor.

Really? Ew. That's much worse. I assumed it was just some sort of failed translation.

[jscheuer1]

All kidding aside, IMHO - PHP should stand for:

Preprocessed Hypertext Protocol

However, I will bow to its creators and/or keepers, as to what they envision it standing for.