RAID (Redundant Array of Independent Disks) is a data storage virtualization technology that combines multiple physical disk drive components into a single logical unit to improve performance and provide redundancy. There are different RAID levels that distribute and protect data across disks in various ways. RAID 0 stripes data across disks for increased speed but provides no data protection. RAID 1 mirrors the same data onto two disks, providing fault tolerance if one disk fails. Higher RAID levels like 3, 4, and 5 provide redundancy through parity data stored on dedicated disks while still allowing for parallel I/O performance.