RAID levels refer to different configurations of Redundant Array of Independent Disks that enhance data storage performance and reliability. Each level combines multiple hard drives in various ways to achieve specific goals, such as increased speed, redundancy, or both. Common RAID levels include RAID 0, which offers improved performance but no data protection, and RAID 1, which mirrors data for redundancy. Other levels, like RAID 5 and RAID 6, provide a balance of performance and data protection by using parity information. RAID 5 requires at least three drives and can withstand a single drive failure, while RAID 6 can handle two drive failures, making it more resilient.