File sharing employs a client/server model. A computer that shares file systems with other computers on a network acts as a server. Files are physically owned and managed by the server machine. A computer that accesses file systems shared by the server acts as a client of the server machine. Acting on behalf of its applications, the client makes requests to a server to access data in a file or to perform file manipulations. A single machine may be both a client and a server, making it possible to share its local file systems and to access remote file systems.