Redundant array of independent disks (RAID) is a type of storage that writes data across multiple drives within the same system to accomplish performance or redundancy goals not attainable with one large drive. This array of drives appears to the computer as a single logical storage unit or drive.
Different configurations are expressed as numbers, such as RAID 0, RAID 1, or RAID 5. Each RAID type gives users different benefits (increased performance, greater fault tolerance, or a combination of both), depending on how it writes and distributes your data.