ISTA 230 Introduction to Web Design (Spring 2017)

ISTA 230 Resources

Note: Windows treats file extensions as case-insensitive, i.e. .HTML is the same as .html. However other operating systems do not and will treat MyDocument.HTML and MyDocument.html as two different files. Therefore it is good practice to always treat your files as case-sensitive for maximum compatibility. This is especially crucial if you are going to use the files on the Internet. It is strongly recommend that you get into the habit of using all lower-case letters for all file extensions.

Below are steps for changing file extensions in Windows. Please select which version of Windows you are running and follow the steps given. If you have any trouble or if the instructions below are incorrect, please feel free to contact me at jmspargu@email.arizona.edu.


Windows 10

Click Start and then click File Explorer.

Windows File Explorer

Click the View tab in File Explorer and then click the Options button (or click the drop down menu and click Change folder and search options)

Click View and click Options

Click the View tab at the top of Folder Options. To see file extensions, uncheck Hide extensions for known file types.

Windows 8

Open Folder Options by clicking the Start button, clicking Control Panel, clicking Appearance and Personalization, and then clicking Folder Options.

Click the View tab. Under Advanced settings, clear the "Hide extensions for known file types" check box and then click OK. Now you should be able to see the file extension:

Windows Explorer

Right-click the file name and select Rename (or left click and hold down the button for one second). Enter the new extension like so:

Changing the extension

After entering the new extension, hit the Enter key. Windows will give you a warning that the file may not work properly. This is quite safe - if the file does stop working you can always change the extension back (just make sure you remember what it was!).

It's also possible that you might get another message telling you that the file is "read-only". In this case either say yes to turning off read-only, or right-click the file, select Properties and uncheck the Read-only box.

If you do not have permission to change the file extension, you may have to login as Administrator. Another option is to make a copy of the file, rename the copy and then delete the original.


Windows Vista / Windows 7

The first thing to do is open Windows Explorer (or My Computer) and view the file you wish to change. We'll use the example of a file called MyDocument.txt which we want to change to MyDocument.html. When we browse to the file it looks like this:

Windows Explorer

You'll notice that the file does not appear to have an extension - it's just called MyDocument. This is because Windows is sometimes configured to hide known extension names. Go to Organize > Folder and Search Options, then click the View tab. Uncheck the box titled "Hide extensions for known file types" like so:

Folder Options Window

Click OK or Apply. Now you should be able to see the file extension:

Windows Explorer

Right-click the file name and select Rename (or left click and hold down the button for one second). Enter the new extension like so:

Changing the extension

After entering the new extension, hit the Enter key. Windows will give you a warning that the file may not work properly. This is quite safe - if the file does stop working you can always change the extension back (just make sure you remember what it was!).

It's also possible that you might get another message telling you that the file is "read-only". In this case either say yes to turning off read-only, or right-click the file, select Properties and uncheck the Read-only box.

If you do not have permission to change the file extension, you may have to login as Administrator. Another option is to make a copy of the file, rename the copy and then delete the original.


Windows XP

The first thing to do is open Windows Explorer (or My Computer) and view the file you wish to change. We will use the example of a file called myfile.txt which we want to change to myfile.html. It looks like this in Windows Explorer:

Windows Explorer

At this stage you might notice that your file does not appear to have an extension (in the above example it would simply be called myfile). This is probably because you have Windows set to hide extension names. Go to Tools > Folder Options, then click the View tab. Uncheck the box titled "Hide extensions for known file types" like so:

Folder Options Window

Click OK. Now you should be able to see the file extensions for all files. Right-click the file name and select Rename. Enter the new extension like so:

Changing the extension

After entering the new extension, hit the Enter key. Windows will give you a warning that the file may not work properly. This is quite safe - if the file does stop working you can always change the extension back (just make sure you remember what it was!).

If you get another message telling you that the file is "read-only" and asking if you want to turn read-only off, say yes.