Buses are the basic transportation lines for moving data, instructions, addresses, and other information inside a computer.
Some writers use the term buss with a double 's'.
The size or width of a bus is how many bits it carries in parallel. The speed of a bus is how fast it moves data along the path. The capacity of a bus is how much data it can carry in a second. This is called double pumping the bus. An internal bus is a bus inside the processor, moving data, addresses, instructions, and other information between registers and other internal components or units.