The .bak file extension is used for general backup files. A large number of applications and computer processes use the .bak extension to create backups of documents that the program is creating.
The .bak file extension is a common file extension for the files that are created by the auto-save features that are found in many computer applications. For example, when you are editing a document in Microsoft Word and the auto-save feature kicks in, a .bak file will be created.
Files with the .bak extension are also commonly created before your computer begins to execute a complex operation, ensuring your data will be restored if something happens during the process.
These files are normally automatically deleted by the application that created them when the file is no longer needed.
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