A differential backup is a type of data backup that saves only the changes made since the last full backup. This means that if you perform a full backup on Sunday, a differential backup on Monday will include all changes made since Sunday. This method helps to reduce the amount of storage space needed and speeds up the backup process compared to full backups. When restoring data, a differential backup requires the last full backup and the most recent differential backup. This makes recovery faster and simpler than using multiple incremental backups, which only save changes since the last backup. Overall, differential backups are an efficient way to protect data while minimizing storage use.