Server Message Block (SMB) is a network protocol used for sharing files, printers, and other resources between computers. It allows applications to read and write to files on remote servers, enabling users to access shared data over a network. SMB operates primarily in Microsoft Windows environments but is also supported by other operating systems. The protocol works by sending requests from a client to a server, which then responds with the requested data or action. SMB can also provide authentication and encryption, ensuring secure communication between devices. It is commonly used in local area networks (LANs) for efficient resource sharing.