Which backup method saves only the data that has changed since the last backup?

The method that saves only the data that has changed since the last backup is known as an incremental backup. This approach is efficient in terms of time and storage, as it focuses solely on the data modifications made since the last backup, whether that was a full or incremental backup. Consequently, this method reduces the amount of data that needs to be backed up during each session, which speeds up the backup process and conserves storage resources.

When performing an incremental backup, only files that have been created or altered since the most recent backup are saved. This means that after the initial full backup, subsequent backups will only capture the changes. For example, if a user performs a full backup on Sunday and then incremental backups on Monday, Tuesday, and Wednesday, only the changes made on Monday, Tuesday, and Wednesday would be included in those incremental backups, respectively.

In contrast, full backups capture all data every time they are performed, differential backups save all changes made since the last full backup, and mirrored backups create a precise copy of the original data without retaining older versions or changes. These alternatives can often involve more time and storage than the incremental backup method, thus highlighting the practicality of using incremental backups in many environments.