Chassis– A computer case for any type of computer.

Tower case – The largest type of personal computer case. Tower cases stand vertically and can be as high as two feet tall. They have more drive bays and are a good choice for computer users who anticipate making significant upgrades.

desktop case – A computer case that lies flat and sometimes serves double-duty as a monitor stand.

VGA (Video Graphics Array) port – A 15-pin analog video port popular for many years. Also called DB15 port, DE15 port, or HD15 port. 

DB15 port – See VGA (Video Graphics Array) port.

HD15 port – See VGA (Video Graphics Array) port.

Analog – A continuous signal with infinite variations. Compare with digital, which is a series of binary values—1s and 0s.

Digital – A signal consisting of a series of binary values— 1s and 0s. Compare with analog.

S-Video port – A 4-pin or 7-pin round video port that sends two signals over the cable, one for color and the other for brightness, and is used by some highend TVs and video equipment.

DVI (Digital Video Interface) port – A port that transmits digital or analog video.

HDMI (High-Definition Multimedia Interface) port – A digital audio and video port currently used on televisions and other home theater equipment and is often used to connect a computer to home theater equipment.

DisplayPort – A port that transmits digital video and audio (not analog transmissions) and is slowly replacing VGA and DVI ports on personal computers. Also see Thunderbolt port.

Thunderbolt port – A port that transmits both video and data on the same port and cable. The port is shaped the same as the DisplayPort and is compatible with DisplayPort devices.

Network port – A port used by a network cable to connect to the wired network. Also called an Ethernet port or RJ-45 port.

Ethernet port – See network port.

RJ-45 port – A port that looks like a large phone jack and is used by twisted-pair cable to connect to a wired network adapter or other hardware device. RJ stands for registered jack. Also called Ethernet port. 

Audio ports – A port that can be used by a microphone, audio in, audio out, and stereo audio out. Also called a sound port.

S/PDIF (Sony/Philips Digital Interface) sound port – A port that connects to an external home theater audio system, providing digital audio output and the best signal quality. 

optical connector – A connector used with a fiber-optic cable.

USB (Universal Serial Bus) port – A type of port designed to make installation and configuration of I/O devices easy, providing room for as many as 127 devices daisy-chained together.

FireWire port – A port used for high-speed multimedia devices such as camcorders. Also called an IEEE 1394 port. 

IEEE 1394 port – See FireWire port. 

PS/2 port – A round 6-pin port used by a keyboard or mouse. 

serial port – A male 9-pin or 25-pin port on a computer system used by slower I/O devices such as a mouse or modem. Data travels serially, one bit at a time, through the port. Serial ports are sometimes configured as COM1, COM2, COM3, or COM4. Also called DB9 port. 

DB9 port – See serial port. 

parallel port – An outdated female 25-pin port on a computer that transmitted data in parallel, 8 bits at a time, and was usually used with a printer. Parallel ports have been replaced by USB ports. Also called an LPT1 port, LPT2 port and LPT port. 

LPT port – See parallel port. 

modem port – A port used to connect dial-up phone lines to computers. 

internal components – The main components installed in a computer case.

motherboard – The main board in the computer, also called the system board. The CPU, ROM chips, DIMMs, RIMMs, and interface cards are plugged into the motherboard. 

main board- See motherboard. 

central processing unit (CPU)- Also called a microprocessor or processor. The component where almost all processing of data and instructions takes place. The CPU receives data input, processes information, and executes instructions. 

Processor- See central processing unit (CPU)

heat sink- A piece of metal, with cooling fins, that can be attached to or mounted on an integrated chip package (such as the CPU) to dissipate heat.

expansion card- A circuit board inserted into a slot on the motherboard to enhance the capability of the computer. 

DIMM (dual inline memory module)- A miniature circuit board installed on a motherboard to hold memory. 

RAM (random access memory)- Memory modules on the motherboard containing microchips used to temporarily hold data and programs while the CPU processes both. Information in RAM is lost when the computer is turned off. 

video memory- Memory used by the video controller. The memory might be contained on a video card or be part of system memory. When part of system memory, the memory is dedicated by Windows to video. 

hard drive- The main secondary storage device of a computer. Two technologies are currently used by hard drives: magnetic and solid state. Also called hard disk drive (HDD).

hard disk drive (HDD)- See hard drive. 

power supply- A box inside the computer case that receives power and converts it to provide power to the motherboard and other installed devices. Power supplies provide 3.3, 5, and 12 volts DC. Also called a power supply unit (PSU). 

power supply unit (PSU)- See power supply. 

form factors- A set of specifications on the size, shape, and configuration of a computer hardware component such as a case, power supply, or motherboard. 

ATX (Advanced Technology Extended)- The most common form factor for computer systems presently in use, originally introduced by Intel in 1995. ATX motherboards and cases make better use of space and resources than did the earlier AT form factor.

20-pin P1 connector- Used by an older ATX power supply and motherboard and provided +3.3 volts, +5 volts, +12 volts, −12 volts, and an optional and rarely used −5 volts.

24-pin P1 connector- Used by ATX Version 2.2 power supply and motherboard and provides additional power for PCI Express slots

4-pin 12-V connector- An auxiliary motherboard connector used for extra 12-V power to the processor. 

8-pin 12-V connector- An auxiliary motherboard connector used for extra 12-V power to the processor, providing more power than the older 4-pin auxiliary connector.

Molex connector- A 4-pin power connector used to provide power to a PATA hard drive or optical drive.

SATA power connector- A 15-pin flat power connector that provides power to SATA drives.

PCIe 6/8-pin connector- A power cord connector used by high-end video cards using PCIe x16 slots to provide extra voltage to the card and can accommodate a 6- hole or 8-hole port. 

PCI (Peripheral Component Interconnect)- A bus common to personal computers that uses a 32-bit wide or a 64-bit data path. Several variations of PCI exist. On desktop systems, one or more notches on a PCI slot keep the wrong PCI cards from being inserted in the PCI slot.

ATX12V power supply- An ATX Version 2.1 power supply that provides an extra 12 V power cord with a 4-pin connector to be used by the auxiliary 4-pin power connector on motherboards used to provide extra power for processors. 

PCI Express (PCIe)- The latest evolution of PCI, which is not backward-compatible with earlier PCI slots and cards. PCIe slots come in several sizes, including PCIe x1, PCIe x4, PCIe x8, and PCIe x16.