What type of backup saves only the files that have changed since the last backup?

The backup type that saves only the files that have changed since the last backup is known as an incremental backup. This method is efficient because it reduces the amount of data that needs to be saved after the initial full backup. When an incremental backup is performed, it only captures data that has been altered or created since the last backup occurred—whether that was a full backup or any previous incremental backup. This approach can significantly conserve storage space and decrease the time required for backup operations.

For instance, if you perform a full backup on day one, then on day two you make some changes, the incremental backup on day two will only save the changes made since the full backup on day one. If additional changes occur on day three, the incremental backup on that day will only include changes since the incremental backup from day two. This chain of backups can speed up the process of recovery, as you will only need to restore the last full backup and all subsequent incremental backups to recapture the most current state of your system.

Differential backups, while similar, save all changes made since the last full backup, leading to larger backup sizes over multiple runs, as each differential backup accumulates changes. A full backup captures all data in one instance without regard to previous backups