System Management Bus
(SMBus, SMB) A simple two-wire bus used for communication with low-bandwidth devices on a motherboard, especially power related chips such as a laptop's rechargeable battery subsystem (see Smart Battery Data). Other devices might include temperature sensors and lid switches.
A device can provide manufacturer information, indicate its model/part number, save its state for a suspend event, report different types of errors, accept control parameters, and return status. The SMB is generally not user configurable or accessible.