What Kind Of File Is That?
Sometimes you’ll see a file with an extension that you’re unfamiliar with.
Short Info About Extensions
(If you’re using Windows, and open a folder and don’t see the filename extensions, you can turn them back on. Have a look at the instructions on The File Extension Source for Windows XP, Windows Vista and Windows 98 users.)
A filename extension is the characters after the last period (dot) in the filename.
Eg: mypresentation.pdf has an extension “pdf”. A filename of mydocument.august.doc has an extension of “doc”. Don’t worry about having 2 dots/periods in the filename — the extension is only the characters after the LAST dot.
One that might trick you: myfile.doc.exe is NOT a “doc” file, it is an “exe” file. Be wary of these in email attachments!
In the early days, Windows computer file names (under the DOS operating system) were limited to what was know as the “8.3 format” — 8 characters for the name, plus a maximum of 3 characters as the extension. At times the filenames could be quite hard to decipher without opening the file! Thankfully that’s changed nowadays (spaces in file names weren’t allowed before Windows 95. But spaces aren’t good anyway for files that might end up being linked online: as the unix file system treats the space as “%20″ — so my file.doc becomes my%20file.doc.
The computer uses this extension to “associate” the file with particular software programs you have installed. So, if you have a file with a “pdf” extension, and you have the free Adobe Reader software installed, when you “launch” the file or open it, the computer will open the associated program (Adobe Reader) and then open your file for display.
I Don’t Know That Extension!
Occasionally you’ll come across a file with an extension you’ve never seen before. There’s a great free website, called The File Extension Source, that can provide the answer for you. It works just about all of the time.
But not always!
For example, today I came across a file with the extension “.mgmf” — I searched The File Extension Source, but there was no answer. So I searched through Google, and eventually came across MindGenious — this a proprietary extension for mind mapping files.
Now I know!
