A .bak file is a backup file that contains the details or information related to a software system, the contents of a database, or another file. When a program is about to overwrite an existing file, the program may first make a copy of the existing file, with .bak appended to the filename. This common .bak naming scheme makes it possible to retrieve the original contents of the file in case of a failed write that corrupts the file, which could be caused by an operating system crash, power outage, or disk space exhaustion.
BAK files are typically backups of documents, databases, projects, or other data. Many programs automatically create BAK files to back up users data. Others allow users to manually create BAK files. These files are often stored alongside the data theyre backing up or in a separate directory named Backup or Backups. There is no standardized format for creating .bak files, and each program that creates .bak files can determine how to format them.
