The actual exchange of information between an NFS client and server is performed by the underlying Remote Procedure Call (RPC) protocol. NFS functionality is therefore described not in terms of specific protocol operations, but by delineating the different actions that a client may take on files residing on a server. In the original version of NFS, NFSv2, these are called NFS server procedures.

Each procedure represents a particular action that a client may perform, such as reading from a file, writing to a file, or creating or removing a directory. The operations performed on the file require that the file be referenced using a data structure called a file handle. As the name suggests, the file handle, like the handle of a real object, lets the client and server “grasp” onto the file. The Mount protocol is used to mount a file system, to enable a file handle to be accessed for use by NFS procedures.

NFS version 3 uses the same basic model for server procedures, but makes certain changes. Two of the NFSv2 procedures were removed, and several new ones added to support new functionality. The numbers assigned to identify each procedure were also changed.