Common Internet File System
(CIFS) An Internet file system protocol, based on Microsoft's SMB. Microsoft has given CIFS to the Internet Engineering Task Force (IETF) as an Internet Draft. CIFS is intended to complement existing protocols such as HTTP, FTP, and NFS.
CIFS is more flexible than FTP. FTP operations are carried out on entire files whereas CIFS is aimed at routine data access and incorporates high-performance multi-user read and write operations, locking, and file-sharing semantics.
CIFS is probably closest in functionality to NFS. NFS gives random access to files and directories, but is stateless. With CIFS, once a file is open, state about the current access to that file is stored on both the client and the server. This allows changes on the server side to be notified to the clients that are interested.