View Full Version : How do I identify a file extension?

07-02-2009, 02:08 PM
Hi, I have been sent a file but I canít open it. How do I find out what type of file extension it is (eg, .doc, .avi, .flv etc...) so I can find the right programme? I tried right clicking on file/properties, but it just says "Type of file: File". I can see the file name, size and date modified, but not the file extension. I'm running XP (coz Vista is of the devil!!). Your help in simple to understand non techy language would be appreciated. Cheers :dogeye:

Speedy Gonzales
07-02-2009, 02:11 PM
Ask whoever sent it ,to tell you what program you need to open it

If they dont know, dont open it / delete it

And if you dont know who sent it / where it came from, dont open it

07-02-2009, 02:19 PM
That means you dear friend FORGOT TO ADD AN EXTENSION! It could be any files from DOC to ODP, from EXE to APP (Mac OS X application).

What I'll say is to try Trial and Error:

1) Guess what type of file it could be. Is it a picture, document, music, video, or something else? You may be able to guess from a well-named file.

2) Try opening it with different programs. If weird things happen, then it's the wrong program. Note: for example, if the file is actually .xls, and you are opening it with Excel 2007, a dialog box may appear saying that the file type is inconsistent or something like that (because the default format for Excel 2007 is .xlsx not .xls). But pressing "yes" would display the file quite well.

3) If you don't want to bother, or you can't figure it out, try using TrID, a program that figures out the extension by its binaries (getting too complicated theories ahead... I don't get it either). download it here (http://mark0.net/download/trid_w32.zip): it's only 25k big.

P.s. I don't really know what I can do, even under Vista. So you don't have to worry about Vista too much :)

07-02-2009, 02:26 PM
Just found a few new method here:

1) The easiest way is to use Word. In Word Ctrl-O to bring out the Open dialog, and in Types, instead of choosing a type, scroll down to the bottom, which says "Recover from any text files". By extracting the texts from the files, you can probably guess what it's talking about, but it may not work with music, pictures or video.

2) If you feel bored, you can use EditPad Pro to look directly into the binaries of the file. Search for clues inside the files, but why don't you read this:

When looking into files, pay particular attention to the first few characters in the file. There are some standard indicators for various common file types...

* If the first two characters are "BM" the file may be a .BMP bitmap image.

* If the first two characters are "PK" the file may be a .ZIP archive file.

* If the first two characters are "MZ" the file may be an .EXE executable file.

* If the first four characters are "%PDF" the file may be an Adobe .PDF file.

* ...and so on.

07-02-2009, 02:35 PM
Thanks for your help.......... I mailed the person who sent it to me and they say its a media file copied out of their internet temp folder, but they don't have an extension either, and want me to see if i can open it. I have virus scanned it and it is sweet. I downloaded Trid, but Trid refuses to open?? No joy with Word either. Any other ideas??

07-02-2009, 02:49 PM
Uh... choose between one of these file formats: .avi, .mpg, .flv (very common, but won't open with Flash Player), .mp4, .swf (not so probable though). Try opening it with VLC Media Player (which is very versatile, but can't handle .flv formats), but I like KMPlayer better.

07-02-2009, 02:59 PM
If in doubt, just open it on a linux system - there, the file extension doesn't matter at all, and the system will figure out what is supposed to be done with it based on the file content.

07-02-2009, 03:20 PM
I have sorted it. I downloaded FLVPlayer and droped the 'unknown' file into it and it played. I then added the extension .flv to the file name and waht do you know, it works!! All is good, thanks for your help:thanks

07-02-2009, 03:56 PM
That's good:thumbs:!