A collection of wires and software protocols that allow for the insertion of printed circuit boards (expansion boards/cards) in a computer. Traditionally, PCs utilized an ISA expansion bus. In recent years, however, the ISA bus has been replaced in nearly all new PCs with a PCI bus for performance reasons.
A group of control lines that provide a buffered interface to devices located either on the system board or on cards that are plugged into expansion connectors. Common expansion buses included on the system board are USB, PC Card, and PCI.
An expansion bus is made up of electronic pathways which move information from your CPU and RAM to all of your other peripheral devices such as a microphone, monitor, telephone line, and printer, which all connect to ports on the back of your computer.