121. File Types: The Power of a
By Andrew D. Wright
Names have power. In many old stories and traditions to know the true name
of someone was to have control over them.
On Windows-based computers, most files have a true name that is hidden
from you by default. This true name usually ends in a three letter
extension, a handy hold-over from Microsoft's early MS-DOS days.
What a Windows file is and what you can do with it will depend on this
extension. Some files, such as text files with a TXT extension, are
harmless. Other files can be dangerous.
The first thing to do is set your Windows Explorer to show these file type
extensions. Once you can see them, you'll have a powerful tool in your
Open Windows Explorer by pressing the Windows key on your keyboard and the
letter e at the same time. If your keyboard does not have a Windows key,
usually set between the Alt and Ctrl keys on the bottom row, then go to
the Windows Start button then Run and type in: explorer then hit Enter.
When Windows Explorer opens, click on Tools then Folder Options. Select
the View tab and uncheck the box marked: Hide extensions for known file
types. Click OK and next time you open Windows Explorer (or browse your
files through the Windows Explorer interface) you'll see the file type
extension in the file names.
In MS-DOS, Microsoft's first operating system, all file names had to be no
more than eight letters long with a dot and a three letter file type
extension at the end.
With the release of Windows 95, this restriction was lifted and files
could be named anything. Underneath the hood though, Windows kept a record
of files in the old eight letter: three letter format.
By now most people are familiar with a number of different data formats,
even if they are not computer people. An MP3 file is an audio file format,
a JPG file is a picture and so on.
These days the file extension does not have to be limited to just three
letters, but most file names keep to this rule anyway.
Some file types are called executable, which means that the file is a
program that can run commands on your system. The most common executable
file types are: BAT, COM, EXE, PIF, and SCR. There are a couple of dozen
file formats that can be considered as executable so it is a good idea to
check if you are not sure what a file is, before clicking on it to run it.
Windows knows about many file extensions but is a bit thick when it runs
into one it doesn't know. Unfortunately the Windows file extension lookup
service is not very good. The best idea is to open a search engine and do
a search for the file type. This will usually give you information on what
kind of file you have and what program would be needed to open it.
To associate a program to open a particular kind of file Windows does not
know about, or change a program association already set in place, open
Windows Explorer and right click on the file. Select Open With and look at
the list of programs Windows suggests using to open the file.
Click Choose Program and browse your computer to find the program folder
and the EXE program file. Clicking on the little check box that says to
always use the selected program will set things so just double clicking on
that file type in the future will open the file using the program you have
Wikipedia's List of File Extensions:
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Originally published 14 December 2007