SMB, or Server Message Block, is a network protocol primarily used for sharing files, printers, and serial ports between computers on a local network. Developed by IBM and later enhanced by Microsoft, SMB enables applications and users to read, write, and request services from devices on the network. It is commonly used in Windows environments but is also supported by other operating systems. SMB operates over TCP/IP and has several versions, with newer versions offering improved security features. However, older SMB versions have been exploited in cyberattacks, making secure configuration and updates essential for protecting network resources.