Windows hides file extensions by default in order to try and keep things simple. Here’s how to enable file extensions so you can change them.

Computer files have two parts to their names: a descriptive name and a file extension. For example July report.doc is a file created by Microsoft Word. You know this because of the .doc extension.

Similarly Umbrella.mp3 is a music file which can be opened by any application which can handle mp3 files.

Because these are common (or known) types of file, Windows doesn’t display the .doc or .mp3 as it’s unnecessary.

Confusingly you’re allowed to have multiple full stops ‘.’ in a filename, which means you can rename a file from July report to The full file name is but you see only

It’s easy to think you can change a file’s extension by renaming the file, but if it’s a known file type – and therefore the extension is hidden – all you’re doing is appending to the filename when you add .txt or .m4r. For example, renaming Umbrella to Umbrella.m4r doesn’t change its file extension; the file has simply become Umbrella.m4r.mp3 and it still an mp3 file.

If you did want to convert a file to a different format, you need to use the appropriate conversion software. You can use iTunes to convert audio files, and open a document in Word and re-save it as a different format, for instance.

How to show file extensions in Windows 7 (and Vista)

1. Open Windows Explorer and click the Organize button towards the top left. Choose Folder and search options from the menu.

2. Click the View tab in the window that opens, then scroll down and untick the box next to ‘Hide file extensions for known file types’

 How to show file extensions in Windows 7

How to show file extensions in Windows 8

It’s simple to turn file extensions on and off in Windows 8. Simply open a File Explorer window (the new name for Windows Explorer) and click the View tab.

 How to show file extensions in Windows 8

Now tick or untick the box next to File name extensions. If the box is ticked, extensions will be shown. If unticked, they won’t. This is the opposite way the tickbox works in Windows 7 and Vista.

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