(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 earlier versions of Windows. In the 1990s, Microsoft renamed SMB to "Common Internet File System" (CIFS), and subsequent enhancements were made to CIFS. Software that enables users at non-Windows computers to access data in Windows machines in the network may use SMB or SMB/CIFS nomenclature.