By default, you can not see the extension of  the files inside Windows Explorer. For example, you cant make difference between an OGG file and MP3. Just see the example screenshot below:

You can not see the file extensions in the above screenshot.

But, you can easily enable Windows 7 to show the extensions. Also, to edit certain file types in Windows 7, showing the extension becomes very important. Because, lot of different files has similar icons to open with the same program, but are of different extensions.

Open any Folder like the above screenshot. Click on the “Organize” tab. Select “Folder and search options” . Like this:

Now Click “View” tab like the screenshot below and scroll down a bit:

Uncheck the box saying “Hide extensions for know file types” ; like this:

Click OK to continue.

You will now able to see the file extensions like the screenshot below:

I this way, you can show the extensions of the files in Windows 7.