The primary function of a backup system in IT is to create and maintain copies of data to prevent loss due to failures, disasters, or accidental deletions. These systems ensure that critical data is preserved and can be restored in case of any unforeseen issues. Backup strategies may include full, incremental, or differential backups, and should adhere to a defined schedule to guarantee data freshness. By implementing reliable backup systems, organizations can enhance their data recovery capabilities and minimize downtime.