What is file extension? It is a suffix name of a file to show what kind of format the file is, and it is can also called file format which makes the computer work to its file as the type of file itself. In Windows, it limit the file extension name to 3 characters.
.mp3 is a file extension for Media Player 3, it's a patented digital audio encoding format. We are sure you know this file, when you are listening the music file, usually it is extended by '.mp3'. If you click the file with .mp3 at the end of the filename, the file will be opened with music application like Winamp, Windows Media Player, or other music media player, depending on what you've installed it in your computer.
.doc is a file extension for Microsoft Word, and if you click the file with .doc at the end of the file name, it will be opened by Microsoft Windows.
If you rename a music file, example music.mp3 to be music.doc, that music file automatically will be opened by Microsoft Word if you click it and Microsoft Word will not recognize the file and the song can not be played.
It means the file extension has unique application to open it.
Why i can not see the file extension in my computer?
Defaultly, Windows hides known file extension and only shows known file extension, remember what you have read the example above. mp3 and doc are usually known by computer, so those extension are hidden.
How do my computer recognize the file extensions?
Easy, your computer recognize the file if you have application to open it installed in your computer. From the example above, if you uninstall any Media Player or Microsoft Word, your computer will not recognize the .mp3 or .doc extension anymore.
How do i show the file extension in my computer?
In Windows XP, open 'My Computer' and click 'Tools' at the top of the window and click 'Folder Options', After Folder Options window is opened, switch the tab to 'View' and scroll down until you see 'Hide extensions for known file types', unmark it and click "OK".
In Windows 7, open 'My Computer' and click 'Folder and search options'. After Folder Options window is opened, do the same like the steps in Windows XP above.
What are benefits of showing extensions?
You may know what the extension is and what application can open its file. For safety, if you see folder icon with '.exe' at the end of the filename, it means fake folder or we can call it virus, if you click it then the virus will be activated.
Which Windows this trick is working?
Almost all version of Windows, from XP, 2000, 2003, Vista, and 7. The lower version has different step but similar to the steps above.