Computer Dictionary/Common Internet File System
CIFS runs on top of TCP/IP and uses the Internet's [[Computer Dictionary/Domain Name Service|Domain Name Service]] (DNS). It is optimised to support the slower speed dial-up connections common on the Internet.
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.