In computer networking, Server Message Block (SMB, also known as Common Internet File System, CIFS) operates as an application-layer network protocol mainly used to provide shared access to files, printers, serial ports, and miscellaneous communications between nodes on a network. It also provides an authenticated inter-process communication mechanism. Most usage of SMB involves computers running Microsoft Windows, where it is often known as "Microsoft Windows Network". When discussing SMB, one should distinguish: