Redundant Array of Independent Disks, or RAID, is a way of keeping content on multiple hard drives simultaneously. A RAID can be software or hardware depending on the drives that are used - physical or logical ones, yet what’s common between them is the fact that they all function as just one single unit where info is saved. The top advantage of employing a RAID is redundancy as the info on all the drives shall be the same at all times, so even in the event that some drive fails for whatever reason, the information will still be present on the rest of the drives. The general performance is also enhanced since the reading and writing processes could be split between various drives, so a single one won't be overloaded. There are different sorts of RAIDs where the efficiency and fault tolerance can vary depending on the specific setup - whether info is written on all of the drives in real time or it's written on one drive and afterwards mirrored on another, what amount of drives are used for the RAID, etcetera.