A redundant array of independent disks, or RAID, is a way of storing the same data in different places (where the term redundant comes from) on multiple hard disks.
There are many ways to use RAID and there are several different types of array. Some use multiple disks to increase performance – think a two or three lane road instead of single, that has to serve traffic going in two directions – while others are used to increase reliability. Additionally, there is a third type of RAID that offer the best of both worlds; all of which we've explained here.
