Network Attached Storage (NAS) is a computer data storage server, which is attached to a computer network. The file-level server provides data access to a diverse group of clients. It consists of one or many storage drives, which are arranged in redundant storage containers (RAID). It is a specialized computer, which is designed to act as a purpose-built server and helps in sharing files over the network. NAS acts as both, file system and storage system. This feature makes it a better option than SAN (Storage Area Network), which offers just block-based storage.
NAS devices can be broadly divided into three categories – Computer-Based NAS, ASIC based NAS, and Embedded System Based NAS. Along with providing the centralized storage to client computers, NAS also helps lower-cost systems, such as, fault-tolerant and load-balancing emails, and web server systems.