A Redundant Array of Independent Disks, or RAID, is a data storage technology that combines multiple hard drives into a single unit. This setup improves performance and provides data redundancy, meaning that if one drive fails, the data can still be accessed from the other drives. RAID can be configured in various levels, such as RAID 0, which focuses on speed, and RAID 1, which emphasizes data protection by mirroring data across drives. By using RAID, users can enhance both the reliability and efficiency of their data storage systems.