The Free On-line Dictionary of Computing (18 March 2015):
The bus (connections between and within the
CPU, memory, and peripherals) used to carry data. Other
connections are the address bus and control signals.
The width and clock rate of the data bus determine its data
rate (the number of bytes per second it can carry), which is
one of the main factors determining the processing power of a
computer. Most current processor designs use a 32-bit bus,
meaning that 32 bits of data can be transferred at once. Some
processors have an internal data bus which is wider than their
external bus in order to make external connections cheaper
while retaining some of the benefits in processing power of a
See also data path.