As you already know, each file type in Windows is associated with a particular application on your computer. In an effort to be “user-friendly,” Windows (as well as other operating systems) hide the most important part of a file name from new computer users: the extension. Let’s assume that the reason behind hiding extensions is a “user-friendly” one because there just isn’t another known reason for hiding them. No harm could ever come from seeing an extension, but plenty could be learned from it.

File extensions must be turned on before you can see them, so, from Windows Explorer,

1. Click on the “Tools” menu, and
2. Select “File Options.”
3. Click the “View” tab and
4. Uncheck the box next to “Hide file extensions for known file types” and
5. Click “OK”.

Notice the files in Windows Explorer now show a dot and group of three letters after the file name. That dot and three letter grouping is known as an “extension,” and the extension explains what type of file you are viewing.

Files range from plain text file to image, sound, video and program but without seeing the extension, it is difficult to tell the file type unless it is double-clicked. Now, with visible file extensions you can easyly associate the file with particular application. The following link present a list of the most commonly found extensions on a computer:
http://www.fileinfo.net/common.php

Tags | Howto, Newbie Windows tips, Windows