RAID stands for Redundant Array of Independent Disks. RAID is a method of storing data on multiple hard drives. When disks are arranged in a RAID configuration, the computer sees them all as one large disk. However, they work much more efficiently than a single hard drive.

Because data spans multiple disks, read and write operations can be performed on multiple disks at the same time. This can significantly speed up the access time to the hard drive. Just as multiple processors can increase CPU performance, multiple hard drives may not improve hard disk performance, but it's based on a similar logic.

The benefits of RAID come from a technique called "striping", which divides the stored data among the available drives. Data strips are usually several megabytes in size and are located between drives. The striping system also increases the mean time between failures when reading data. This allows more data to be read accurately in a short time. The benefits of the RAID system are especially noticeable when storing large amounts of data. For this reason, many Web hosts and Internet Service Providers (ISPs) use RAID for data storage for their customers.