What is the .bak File Extension Used For?

Backup Files

Files with the .bak file extension are Backup Files of another document. The .bak files are used by various programs and the Windows operating system to make a copy of a document, program, or data.

.bak files are automatically generated by programs and the Windows operating system. For instance, Windows can make a backup of settings information that are used by it to start up your computer, or access various programs. Examples of files for which Windows create .bak (backup) files are Win.ini and System.ini files.

How to open .bak files

To open a .bak file (both on Windows and Mac Operating System) you need to use the program that created the file. Before you can open a .bak file, you need to first change the file extension to the original file extension. To better understand this, let?s see the following example.

You have a file named thisismydocument.bak (backup file of a Word file) that you need to open. To open the file, just change the extension to .doc (file extension associated with Word files) that is, thisismydocument.doc.

To change the file extension of a file, you need to complete the following two tasks:

  • Clear Hide extensions for known file types.
  • Change the file extension of the file.

The steps illustrated below take you through on how to do this.

Clear Hide extensions for known file types

  1. Click Start and then click My Computer.
  2. Click Tools and then click Folder Options.
  3. Click the View tab.
  4. Clear the box before Hide extensions for known file types.
  5. Click Apply to save the changes.

Change the File extension

  1. Right-click the file whose extension you want to change and then click Rename.
  2. Type the new extension and press Enter.

Firefox Bookmarks Backup Files

The .bak file extension is also associated with the backup files of Firefox bookmark files, typically named bookmarks.bak. The bookmarks.bak file can be used by computer users to restore saved bookmarks if the original bookmarks file is deleted or becomes corrupt.

bookmarks.bak ? File Location

On a Windows PC, the file is located in the C:\Documents and Settings\<username>\ApplicationData\Mozilla\Firefox\Profiles\ folder.

On a Mac PC, the file is located in the /Users/<username>/Library/Application Support/Firefox/Profiles/ folder.

You can use Mozilla Firefox to open .bak files on both Windows and Apple computers.

In case you are unable to open a .bak file even after changing the file extension to the correct file extension, then it is recommended to use a file repair software to open the file.