Backup systems are methods used to create copies of data to prevent loss in case of hardware failure, accidental deletion, or cyberattacks. These systems can be physical, like external hard drives, or cloud-based, where data is stored on remote servers. Regular backups ensure that important information is safe and can be restored when needed. There are various types of backup systems, including full, incremental, and differential backups. A full backup copies all data, while an incremental backup only saves changes made since the last backup. Differential backups save changes since the last full backup, providing a balance between speed and storage efficiency.