RAID stands for Redundant Array of Independent Disks. It is a technology used to combine multiple hard drives into a single unit to improve performance, increase storage capacity, or provide data redundancy. By spreading data across several disks, RAID can enhance read and write speeds, making it beneficial for servers and high-performance applications. There are different levels of RAID, such as RAID 0, RAID 1, and RAID 5, each offering various balances of speed and data protection. For example, RAID 1 mirrors data across two drives, ensuring that if one fails, the data remains safe on the other.