Hardware - The physical, touchable, material parts of a computer or other system. The term is used to distinguish these fixed parts of a system from the more changeable software or data components which it executes, stores, or carries. Computer hardware typically consists chiefly of electronic devices (CPU, memory, display) with some electromechanical parts (keyboard, printer, disk drives, tape drives, loudspeakers) for input, output, and storage, though completely non-electronic (mechanical, electromechanical, hydraulic, biological) computers have also been conceived of and built.

Motherboard - The main printed circuit board in an electronic device, particularly a computer, which contains sockets that accept additional boards ("daughter-boards"). In a (personal) computer, the motherboard contains the bus, the microprocessor and chips used for controlling any built-in peripherals such as the keyboard, text and graphics display, serial ports and parallel ports, joystick and mouse interfaces.

BIOS – (Basic Input/Output System) The part of the operating system of the IBM PC and compatibles that provides the lowest level interface to peripheral devices and controls the first stage of the bootstrap process.

Processor – (Central Processing Unit or CPU) The part of a computer which controls all the other parts. The CPU fetches instructions from memory and decodes them.

ROM – (Read-Only Memory) A type of data storage device which is manufactured with fixed contents. ROM is inherently non-volatile storage - it retains its contents even when the power is switched off. ROM is often used to hold programs for embedded systems since these usually have a fixed purpose. ROM is also used for storage of the lowest level bootstrap software in a computer.

RAM – (Random Access Memory Previously "direct-access memory"). A data storage device for which the order of access to different locations does not affect the speed of access. The most common form of RAM in use today is built from semiconductor integrated circuits, which can be either static (SRAM) or dynamic (DRAM). RAM is still referred to as core by some old-timers.

Clock - A processor's clock or one cycle thereof. The relative execution times of instructions on a computer are usually measured by number of clock cycles rather than seconds. One good reason for this is that clock rates for various models of the computer may increase as technology improves, and it is usually the relative times one is interested in when discussing the instruction set.

Bus - A set of conductors (wires, PCB tracks or connections in an integrated circuit) connecting the various functional units in a computer. There are busses both within the CPU and connecting it to external memory and peripheral devices. The width of the bus, i.e. the number of parallel connectors, determines the size in bits of the largest data item which it can carry. The bus width and the number of data items per second which it can transmit are one of the factors limiting a computer's performance. Most current microprocessors have 32-bit busses both internally and externally. Some processors have internal busses which are wider than their external busses (usually twice the width) since the width of the internal bus affects the speed of all operations and has less effect on the overall system cost than the width of the external bus.

Port - 1. <networking> A logical channel or channel endpoint in a communications system. 2. <operating system, programming> To translate software to run on a different system or the results of doing so.

Serial port - A connector on a computer to which you can attach a serial line connected to peripherals which communicate using a serial (bit-stream) protocol.

Parallel port - An interface from a computer system where data is transferred in or out in parallel, that is, on more than one wire. A parallel port carries one bit on each wire thus multiplying the transfer rate obtainable over a single wire. There will usually be some control signals on the port as well to say when data is ready to be sent or received. The commonest kind of parallel port is a printer port. Disks are also connected via special parallel ports.