RAID 5 is a data storage technology that combines multiple hard drives to improve performance and provide fault tolerance. It uses a technique called striping, where data is split into blocks and distributed across several drives. Additionally, RAID 5 includes parity information, which allows for data recovery in case one drive fails. In a RAID 5 setup, at least three drives are required, but more can be added for increased storage capacity. If one drive fails, the system can still operate, and the lost data can be reconstructed using the parity information stored on the remaining drives.