How to Force Windows Explorer to Always Show You the File Extensions

By default, Windows Explorer hides certain parts of a filename from you. For example, a file named "sample.txt" will appear in Explorer as "sample". Likewise a file named "virus.jpg.exe" will appear to you as "virus.jpg". This behaviour is hazardous, and can potentially cause you to double-click on file like "virus.jpg", thinking that it is just a picture, when it is actually a program "virus.jpg.exe" which you would never have clicked had you really known the filename.
This behaviour also causes a lot of problems, particularly to webmasters trying to fix other problems created by Notepad, and so on.
Fortunately, it's easy to fix this problem in Explorer.

1. Open Windows Explorer (also known as "My Computer" or "Computer" on the Windows desktop and the Start Menu).
2. Click the "Tools" menu on the menu bar in Explorer (the menu bar is at the top of the Explorer window, underneath the window title). Click the "Folder Options" item in the popup menu that appears.
3. A dialog box appears. Click the "View" tab at the top of the window. Look for a setting "Hide file extensions for known file types" and uncheck the box beside it to disable it.
4. Click the button "Apply to All Folders". Then click "Apply" and then "OK".

That's it. You should now be able to see the true extensions of the files in your Explorer windows.