Definition: SMB

(1) (Small to Medium-sized Business) Also called small to medium-sized enterprise (SME), SMBs are companies with approximately 25 to 500 employees. However, some SMBs and SMEs use an upper limit of 5,000. From an IT viewpoint, these numbers mean how many workstations must be managed. See SOHO.

(2) (Server Message Block) The file sharing protocol in DOS and Windows. SMB originated with the NetBIOS protocol used in the first DOS networks and it later migrated to OS/2 and Windows.

In the 1990s, Microsoft renamed SMB to "Common Internet File System" (CIFS), and SMB/CIFS was a common reference for a while. Mac and Linux computers also support SMB to access shared folders on Windows machines. See CIFS, file sharing protocol and Samba.

From Windows to this Mac

These are Mac dialogs showing connections to Windows computers. In the late 2000s, the dialog (top) displayed both SMB and CIFS names, but by 2025 (bottom), CIFS was no longer mentioned.

From Linux to Windows

This example is the file manager from the KDE user interface on a Linux computer. "SMB Shares" are the shared files and folders on the Windows computers in the network.