A system, developed by Microsoft, to allow file sharing across a Windows network. It runs over TCP/IP and and can use DNS to scale over large networks.
Microsoft says CIFS is platform independent, although it is based on an older Windows-specific protocol called the Server Message Block protocol (however, there are implementations for non-Windows systems).
Compare to NFS.
Additional resources
CIFS: A Common Internet File System
Microsoft paper that details CIFS.
