One of Microsoft’s attempts at “user friendliness” is that recent versions of Windows are set to hide file extensions. What’s a file extension? As an example, it is the “.exe” that is at the end of a program’s name.
Unfortunately, Microsoft decided that we don’t really need to know what file extensions are. Even worse, they decided that Microsoft programs including Windows might not always consider the file extension, when deciding which program to use with a file.
Huh? That was a lot of words. Let’s take it in shorter sentences.
A file extension is the ending of a file name. For example, Microsoft Word’s file name is WINWORD.EXE. Word, by default, declares to Windows that it owns files with the extension “.doc”. So, if you double-click on a file ending with .doc, Word will try to open it. Similarly, the Notepad program “notepad.exe” declares ownership of the .txt file extension. [By the way, Windows is not case sensitive, so it views Notepad.exe and notepad.EXE and NoTePaD.EXe as the same thing.]
Finally, by default, you do not see file extensions — Windows hides them.
OK, so what’s the problem?
The problem is that, in older versions of Windows, the period (“.”) was not a valid character for a file name — it was only valid as a separator between the first part of a filename and the file’s extension.
Windows XP, and I think Win2000, changed that. They joined the Linux/Unix naming conventions to an extent with that change. Now, a period is valid within the file name, or even multiple periods, in addition to the one separating the filename from the file extension.
So, you could rename WINWORD.EXE to Win.Word.2000.exe, if you wanted. It would still execute the same program. (Of course, if you did, you would have to change any Word shortcut, too, so that the shortcut still worked.)
Now, let’s look at another case. Say you get an email with an attachment labelled my-neat-pictures-from-the-beach.jpg . We all know .jpg files are image files — picture files — so, it’s safe, right?
Wrong! With the Windows defaults, which hide the file extension, the file might really be my-neat-pictures-from-the-beach.jpg.exe — see the problem? It might really be a program.
The fix is to turn off the Windows setting “hide file extensions.”
Turning Off the “Hide File Extensions” Setting
One of the first things I do on my computers is to turn off the Hide File Extensions setting. I also do this on almost every PC on which I work.
Whether you are using Windows 95, 98, Me, 2000 or XP, the technique is similar.
In Windows XP, open up Windows Explorer. Right-click on the Start button. Then, left-click on Explore.
Click on Tools, Folder Options, View.
Then, uncheck “Hide extensions for known file types.”