1. Technology

Types of Web Files - Common File Types and File Extensions

What Do All Those File Types Mean?


When learning what it takes to build a web page, you'll come across many different types of files. Even though most web pages are run on Unix web servers which, like Macs, don't require file extensions, filename extensions are the most common way to differentiate between files. Once you see a file name and extension, you know what type of file that is, how the web server uses it, and how you can access it.

The Common File Types

The most common files on web servers are:

  • web pages
  • images
  • scripts
  • programs

Web Pages

There are two extensions that are standard for web pages:


There is no difference between these two extensions, you can use either on most web servers.

.html was the original extension for HTML pages on Unix web hosting machines. It references any file that is HTML (or XHTML).

.htm was created by Windows/DOS because of it's requirement for 3 character file extensions. It also references HTML (and XHTML) files, and can be used on any web server, regardless of operating system.

index.htm and index.html
This is the default page in a directory on most web servers. If you want someone to go to your web page, but you don't want them to have to type a file name, you should name the first page index.html. For example http://webdesign.about.com/index.htm will go to the same place as http://webdesign.about.com/. Some web servers call this page "default.htm" and you can change the filename if you have access to the server configuration. Learn more about index.html pages

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