Information, tips and instructions

BAK File

BAK file extension is used to store temporary backup information or reserved copies of the data. Depending on the BAK file initial purpose the data in it could be stored for longer or shorter period of files.

Auto-save BAK files is an example of short living data backup. BAK files are created by the application to store copy of data while the original file is being edited. The purpose of BAK file is to provide data restoration mechanism in case application crashes and the original file gets corrupted. BAK file in this case is only stored for the duration of editing process and deleted when all changes are applied to the original file.

BAK file is not associated with any application and it is not possible to open BAK file by double clicking on it both on Windows and OS X operating systems. But it may still possible to open the file by removing the BAK extension from the file name. Typically, original file name and extension is preserved when BAK extension is appended to the file name. When you remove BAK extension from the file name you will get the original file name with the original file extension. After that you can double click on the file to open it with an application assigned to it.

Sometimes BAK file extension may replace an original file extension. In this case instead of removing BAK file extension from the file name you will need to swap BAK file extension to an original file extension. If you don’t know the original file extension of the file and don’t have an application which created the BAK file, it may be quite problematic to find out what is inside the BAK file. You can look inside the file using hex editor and see if you can infer the file extension from the BAK file contents.