bak is a backup file with a file format extension.
bak
.bak is
A lot of software will create
Generally speaking, the .bak file can be restored by directly renaming and replacing bak with the format of the file. This file can be opened normally.
For a simple example: When the autocad file is moved, sometimes a .bak file is generated. For example, there is now a backup file asdfjk.dwg file asdfjk.bak. To restore a backup file to an official file, you only need to rename the backup file. Replace bak with dwg to open it.
Similarly, if it is a word file backup file, just replace bak with doc. (Can be changed to any file format)
In addition, the encrypted .bak file cannot be opened by modifying and renaming, even if it is opened, it is garbled.