A SAN (storage area network) is a subnetwork of storage devices that are shared with one another over a high-speed network connection. The purpose of a storage area network is to allow all designated users on the network to access multiple storage devices, not only the storage devices installed in their computer. Once a SAN is constructed, and all storage devices are shared in the SAN, it's then connected to the servers accessed by network users.
The primary benefit of a SAN is it decreases the amount of storage required on a network server for multiple users to access the same information. With multiple users' accessing the storage devices, businesses can use the extra network capacity to run more powerful applications and increase the efficiency of the network. SAN's are also used for storage redundancy purposes in case of unexpected natural disaster and loss of data. Large back-up disk arrays can be stored on an off-site location and shared on a SAN where users can access them remotely.