Backup of another document or file, commonly created automatically by software programs or by the operating system; most often just contains a copy of the original file; can be restored to the original by replacing the ".bak" extension by the original extension.
Often BAK files are created by simply appending ".bak" to the original filename. For example, document.doc may have a backup file document.doc.bak.
NOTE: An example program that uses the ".bak" extension is AutoCAD. Windows may also create BAK files for the System.ini and Win.ini files.
Backup of the Firefox bookmarks file; can be used to replace saved bookmarks in case the main bookmarks file becomes corrupted; automatically generated by the Firefox Web browser; typically named "bookmarks.bak"
The bookmarks.bak file is located in the following directories on Windows and Macintosh systems:
C:\Documents and Settings\UserName\Application Data\Mozilla\Firefox\Profiles\[randon-name] Mac
Backup file created by ACT!, an application used for customer relationship management (CRM); contains a backup of CRM data, which includes customer information such as names, address information, and history.
ACT! BAK files are used for restoring data in the event the CRM data is lost. They are usually created on a periodic basis and when upgrading ACT! software.
File created by Finale, a music notation application for playing instruments, vocals, etc.; replaced by the .BAKX file, which was released in Finale 2014; contains backup data for .MUS files; created when MUS files are saved by the user.
To create a BAK file:
You must first enable the backup creation option.
Select Finale [version] → Preferences....
Select "Save and Print" in the list on the left of the "Preferences" window, check the "Make Backups When Saving Files" checkbox, and click OK.
Now when you save your MUS file, a BAK file will be created.