SMB(1) Short for Server Message Block, a message format used by DOS and Windows to share files, directories and devices. NetBIOS is based on the SMB format, and many network products use SMB. These SMB-based networks include Lan Manager, Windows for Workgroups, Windows NT, and Lan Server. There are also a number of products that use SMB to enable file sharing among different operating system platforms. A product called Samba, for example, enables UNIX and Windows machines to share directories and files.
(2) Short for small-to-midsize business, or small-medium business.