The Network File System (NFS) is a client/server application. It allows remote hosts to mount files system over a network and interact with those file systems as like they are mounted locally. The NFS protocol is one of the several distributed file system standards for network-attached storage (NAS).
NFS was originally developed by Sun Microsystems in the 1980’s and it is now managed by the Internet Engineering Task Force (IETF). Network File System versions 2 and 3 allows the User Datagram Protocol (UDP) running over an IP network to provide stateless network connections between clients and server, but NFSv4 requires the use of the Transmission Control Protocol (TCP). The NFS protocol is designed to be independent of network architecture, transport protocol, operating system, and the computer.
NFS allows the user or system administrator to mount (designate as accessible) all or a portion of a file system on a server. The mounted file system on the server can be accessed by the clients with the privileges assigned to each file (read-only or read-write). NFS uses Remote Procedure Calls (RPC) to route requests between clients and servers.