1. An internal electrical pathway along which signals are sent from one part of the computer to another. Personal computers have a processor bus design with three pathways. The data bus sends data back and forth between the memory and the microprocessor divided into an external data bus and an internal data bus. The addrss bus identifies which memory location will come into play. The control bus carries the control unit's signals. From QUECID

2. An internal communication network in a computer system. A typical system includes an address bus, a data bus, and a control bus. The width of the address bus determines the amount of memory that can be addressed by the system. From Linux Guide @FirstLinux