Those little pathways
that channel data
(or as jakohn said it, multiple devices
The word bus
is derived from the latin omnibus
with the idea that several sets of chips
can be connected to the same bus and share the same communication channels.
Three buses are usually within the processor
, the data bus
(for transferring data, duh), the address bus
(for communications between the control unit
) and the control bus
(for transmitting signals between components).