Network-attached storage (NAS) is file-level computer data storage connected to a computer network providing data access to heterogeneous network clients, rather than directly being connected to the computer.NAS devices enable multiple computers to share the same storage space at the same time. These devices are assigned an IP address and can then be accessed by clients (PCs or laptops) via a server, which is within the NAS device (NAS devices are often referred to as NAS servers ) that acts as a gateway to the data.

Some of the big benefits of NAS include the expandability; if more storage space is required, simply add another NAS device and expand the available storage. NAS also brings an extra level of fault tolerance to the network. Fault tolerant measures such as RAID can be used to make sure that the NAS device does not become a point of failure. NAS systems often contain more than one hard disk drive, often arranged into logical, redundant storage containers or RAID arrays for added redundancy/security - thus protecting data in the case of disk failure.