(1) (Small to Medium-sized Business) Also called "SME" (small to medium-sized enterprise), it refers to companies that are larger than the small office/home office (SOHO), but not huge. For example, it typically refers to companies with 25 to 500 employees; however, some SMB/SME ranges use an upper limit of 5,000 employees. From an IT viewpoint, the SMB/SME designation refers to the number of workstations that must be managed, rather than the number of employees in the organization. See SOHO.
(2) (Server Message Block) The file sharing protocol in DOS and Windows. In the 1990s, Microsoft renamed SMB to "Common Internet File System" (CIFS). Software that enables users at non-Windows computers to access data in Windows machines in the network may use either SMB or SMB/CIFS nomenclature. SMB originated with the NetBIOS protocol used in the first DOS networks. It then migrated to OS/2 and Windows. See file sharing protocol, CIFS and Samba.