Network-attached storage (NAS) is a specialized device designed to offer shared storage services to users on a network.

NAS functions as a dedicated file storage solution that provides file-based shared storage to local-area network (LAN) nodes through a standard Ethernet connection. It operates independently on the LAN and consists of one or more hard drives organized into logical, redundant storage configurations, often utilizing RAID (Redundant Array of Independent Disks) technology.

NAS devices can take the form of either hardware appliances or software applications. They are connected to the network and assigned an IP address, enabling both application programs and users to efficiently store and retrieve data. This differs from direct-attached storage (DAS), which is directly connected to a single computer and lacks network capabilities.

One of the notable features of NAS devices is their flexibility and scalability. As storage needs grow, additional capacity can easily be added to the existing setup. A NAS device functions similarly to a file server, providing both storage capabilities and a file system. This contrasts with storage area networks (SAN) and DAS, which are typically seen as disk drives accessible over a network rather than true file servers.

NAS utilizes file-based protocols such as NFS (Network File System), commonly used on UNIX systems; SMB/CIFS (Server Message Block/Common Internet File System), which is prevalent in Microsoft Windows environments; AFP (Apple Filing Protocol), utilized by Macintosh computers; and NCP (Novell Core Protocol), used with OES and Novell NetWare. Notably, NAS units generally do not restrict clients to a single protocol.

The primary advantage of NAS is its ability to provide multiple clients on the network simultaneous access to the same files. This capability is particularly beneficial for enterprises that manage large volumes of data, as it facilitates collaboration among employees working on shared projects without the need to transfer files between individual computers. Additionally, NAS simplifies file sharing across different operating systems by typically supporting a variety of network protocols.

In summary, NAS is a dedicated device that delivers shared storage services to network users. It operates as an independent node within a network, enabling easy file sharing and collaboration among users and applications.