32 Important Computer Parts Explained

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Going over the parts of a computer and its functions will help you understand all the vital components that make up a computer. Learning about these parts is not only a good entry point, but it’s also something good to know for curiosity’s sake.

Computer Case

A computer case, also known as a computer chassis, tower, system unit, or cabinet, is the enclosure that contains most of the components of a personal computer (usually excluding the display, keyboard, mouse, and other peripheral devices such as a printer, scanner, speaker, etc.).

Important Computer Parts Explained

Major Component Locations in Computer Case

  • The motherboard is usually screwed to the case along its largest face, which could be the bottom or the side of the case depending on the form factor and orientation.
  • Form factors such as ATX (Advanced Technology eXtended) provide a back panel with cut-out holes to expose I/O ports provided by integrated peripherals, as well as expansion slots which may optionally expose additional ports provided by expansion cards. Many larger ATX cases can also be used with motherboards of other form factors.
  • The power supply unit mounting point differs from case to case, but the most commonly used locations and their benefits are:
  • The top of the case, usually allowing the PSU’s built-in fan to act as an auxiliary exhaust fan but causes the PSU to be fed air heated by the internal components of the case, thus causing PSU efficiency and lifespan degradation.

  • The bottom of the case, with an (often filtered) vent in the bottom of the case allowing the PSU to draw cool air from the outside.
  • Regardless of the mounting position, the PSU will usually be attached to the case with four screws to support its weight.
  • Most cases include drive bays on the front of the case; a typical ATX case includes 5.25”, 3.5”, and 2.5” bays. In modern computers, the 5.25” bays are used for optical drives (previously used for 5.25” floppy drives), the 3.5” bays are used for hard drives and card readers, and the 2.5” bays are used for solid-state drives.
  • Buttons and LEDs are typically located on the front of the case; some cases include additional I/O ports, temperature, and processor speed monitors in the same area.
  • Vents are often used on the front, back, top, left side panel, and sometimes on the right-side panel of the case. Regardless of their placement, their purpose is either to let cool air into the case or to let hot air out. Larger vents usually allow cooling fans to be mounted via surrounding threaded screw holes. Newer cases include mountings for larger 120 mm or 140 mm cooling fans for quieter operation than 80 mm fans formerly used.
  • An I/O template, or I/O plate, fits around the motherboard’s back panel of external ports. Sometimes provided by the case manufacturer, it is often replaced by the one that comes with the motherboard.


Also referred to as the MB, mainboard, Mboard, mobo, backplane board, baseboard, main circuit board, planar board, system board, or a logic board on Apple computers. The motherboard is a printed circuit board (PCB) and foundation of a computer that is the biggest board in a computer chassis. It allocates power and allows communication to and between the CPU, RAM, and all other computer hardware components.

A motherboard provides connectivity between the hardware components of a computer, like a processor (CPU), memory (RAM/ROM), hard drive, video card, and other components. There are various types of motherboards, designed to fit different types and sizes of computers.

Important Computer Parts ExplainedMotherboard

Each type of motherboard is designed to work with specific types of processors and memory, so they don’t work with every processor and type of memory. However, hard drives are mostly universal and work with a majority of motherboards, regardless of the type or brand.

The main components present on the motherboard are:

CPU (Central Processing Unit) chip

Also known as a processor, central processor, or microprocessor, the CPU is the central processing unit of the computer. A computer’s CPU handles all the instructions it receives from hardware and software running on the computer. The CPU is often referred to as the brain of the computer.

Important Computer Parts ExplainedCPU Chip

Many new computer users may improperly call their computer and sometimes their monitor the CPU. While referring to your computer or monitor, it’s proper to refer to them as either the “computer” or “monitor” and not a CPU. The CPU is a chip inside the computer.

RAM (Random Access Memory) Slots

RAM is a kind of computer memory that can be read and written. It is mainly used to save data and machine code. A RAM device permits data to be read or written in nearly the same amount of time no matter where the data’s physical location is in the memory. Compared to direct-access storage devices like hard drives, CD/DVD, and magnetic tapes, RAM media is much faster for data reading and writing.

Important Computer Parts ExplainedRAM Slots

The RAM is also alternatively referred to as primary memory, temporary memory, short-term memory, or volatile memory. The RAM is considered to be the main memory where the program first gets loaded. 

The RAM is the critical resource that is managed by the operating system. The operating system allocates the main memory required for the program execution.


Northbridge is one of the two chips located in the direction towards North in the motherboard. The main function of Northbridge is to manage the communications between the Central Processing Unit and parts of the motherboard. Northbridge is directly towards Front Side Bus (FSB). Other names for Northbridge are the host bridge and Memory Controller Hub (MCH).

Important Computer Parts ExplainedNorthbridge and Southbridge

Southbridge is another chip of the logical chipset architecture. It is located to the South of the Peripheral Component Interconnect (PCI) bus in the motherboard. The main function of Southbridge is to control the IO functioning.

The Northbridge is the medium that connects Southbridge and the Central Processing Unit. IO Controller Hub is the other name given to Southbridge for its functionality.

BIOS (Basic Input/Output System)

BIOS provides a set of instructions and is responsible for booting the computer. The BIOS performs all the tests needed at startup time. These tests are collectively known as Power On Self Test(POST). The computer contains hardware like a keyboard, monitor, disk drives, etc. their functioning requires interfacing with the operating system. The BIOS provides drivers for basic hardware like keyboard and monitor, mouse, etc. The operating system provides hardware for printers, modems, etc. Drivers for some hardware may not be available in the operating system hence these have to be explicitly installed by the user.

Important Computer Parts ExplainedROM-BIOS

BIOS is typically placed in a chip known as Read-Only Memory(ROM) that comes with the computer. This ensures that the BIOS will always be available even if the hard disk is formatted or replaced. However, in many cases, the content of the ROM is transferred to the RAM when the system is started. This is because the RAM allows quicker access as compared to the ROM. Copying of the content of the ROM to the RAM is known as shadowing.

I/O Port

I/O parts are also referred to as  I/O address, I/O port address is a memory address used by software to communicate with hardware on your computer. On your computer there are 65,536 memory ports that are numbered from 0000h to FFFFh.

Important Computer Parts ExplainedI/O Port

The I/O port assignment can be made either manually using DIP switches or automatically using PnP. When configuring a device’s I/O port, it’s important that it does not share the same port as another device, otherwise hardware conflict occurs.

To view the computer I/O addresses in Windows, open the Device Manager, click View at the top of the Device Manager window, click Resources by type, and then select Input/Output (IO). You will see output similar to the figure shown below.

Important Computer Parts ExplainedDevice Manager window

USB (Universal Serial Bus)

A Universal Serial Bus (USB) is a common interface that enables communication between devices and a host controller such as a personal computer (PC) or smartphone. It connects peripheral devices such as digital cameras, mice, keyboards, printers, scanners, media devices, external hard drives and flash drives. Because of its wide variety of uses, including support for electrical power, the USB has replaced a wide range of interfaces like the parallel and serial port.

Important Computer Parts ExplainedUSB Port

A USB is intended to enhance plug-and-play and allow hot swapping. Plug-and-play enables the operating system (OS) to spontaneously configure and discover a new peripheral device without having to restart the computer. As well, hot swapping allows removal and replacement of a new peripheral without having to reboot.

PCI (Peripheral Component Interconnect) Slot

Peripheral Component Interconnect (PCI) is a  local computer bus for attaching hardware devices in a computer and is part of the PCI Local Bus standard. The PCI bus supports the functions found on a processor bus but in a standardized format that is independent of any given processor’s native bus. Devices connected to the PCI bus appear to a bus master to be connected directly to its own bus and are assigned addresses in the processor’s address space.

Important Computer Parts ExplainedPCI Slot

It is a parallel bus, synchronous  to a single bus clock. Attached devices can take either the form of an integrated circuit fitted onto the motherboard(called a planar device in the PCI specification) or an expansion card that fits into a slot.

AGP (Accelerated Graphics Port) Slot

An Accelerated Graphics Port (AGP) is a point to point channel that is used for high-speed video output. This port is used to connect graphic cards to a computer’s motherboard. It increases the speed at which machines can render graphics while using the system’s resources more efficiently. The primary purpose of an AGP is to convey 3-D images much more smoothly than is possible on a regular PC.

Important Computer Parts ExplainedAGP Slot

ISA (Industry Standard Architecture) Slot

ISA is a type of bus used in PCs for adding expansion cards. For example, an ISA slot may be used to add a video card, a network card, or an extra serial port. The original 8-bit version of PCI uses a 62 pin connection and supports clock speeds of 8 and 33 MHz. 16-bit PCI uses 98 pins and supports the same clock speeds.

Important Computer Parts ExplainedISA Slot

Parallel Port

A parallel port is a type of interface found on computers (personal and otherwise) for connecting various peripherals. The IEEE-1284 standard defines the bidirectional version of the parallel port. In its standard form, it allows only for simple communications from the PC outwards. However, like the RS-232, the parallel port is a standard port of the PC.

Important Computer Parts ExplainedParallel Port

All parallel ports use a bidirectional link in either a compatible, nibble, or byte mode. These modes are relatively slow, as the software must monitor the handshaking lines (up to 100 kbps). To allow high speeds, the enhanced parallel port and extended capabilities port protocol modes allow high-speed data transfer using automatic hardware handshaking.

FDC (Floppy Disk Controller)

A floppy disk controller (FDC) is a specially designed chip that controls the reading and writing functionality of a floppy drive. An FDC can support up to four floppy disk drives at a time. The controller is connected to the system bus of the CPU and appears as a set of I/O ports to the computer. It is usually also linked to a serial bus of the direct memory access (DMA) controller. In an x86 computer, the floppy disk controller uses IRQ 6, whereas interrupt schemes are used on other systems. Data transmission is often done by FDC while in DMA mode.

Important Computer Parts ExplainedFloppy Disk Controller

IDE (Integrated Drive Electronics) Controller

IDE (Integrated Drive Electronics) is a standard electronic interface used between a computer motherboard’s data paths or bus and the computer’s disk storage devices. The IDE interface is based on the IBM PC Industry Standard Architecture  (ISA) 16-bit bus standard, but it is also used in computers that use other bus standards. IDE was adopted as a standard by the American National Standards Institute (ANSI) in November 1990.

Important Computer Parts ExplainedIntegrated Drive Electronics Controller

The ANSI name for IDE is Advanced Technology Attachment (ATA), and the ATA standard is one of several related standards maintained by the T10 Committee. In today’s computers, the IDE controller is often built into the motherboard. Prior to the IDE drive, controllers were separate external devices so IDE reduced problems associated with storage devices and integrated controllers.

CMOS (Complementary Metal-Oxide-Semiconductor) Battery

It is a technology used to produce integrated circuits. CMOS circuits are found in several types of electronic components, including microprocessors, batteries, and digital camera image sensors.

The “MOS” in CMOS refers to the transistors in a CMOS component, called MOSFETs (metal oxide semiconductor field-effect transistors). The “metal” part of the name is a bit misleading, as modern MOSFETs often use polysilicon instead of aluminum as the conductive material. Each MOSFET includes two terminals (“source” and “drain”) and a gate, which is insulated from the body of the transistor. When enough voltage is applied between the gate and body, electrons can flow between the source and drain terminals.

Important Computer Parts ExplainedCMOS

The “complimentary” part of CMOS refers to the two different types of semiconductors each transistor contains — N-type and P-type. N-type semiconductors have a greater concentration of electrons than holes, or places where an electron could exist. P-type semiconductors have a greater concentration of holes than electrons. These two semiconductors work together and may form logic gates based on how the circuit is designed.

Power Supply Connector

A power supply unit (PSU) converts mains AC to low-voltage regulated DC power for the internal components of a computer. Modern personal computers universally use switched-mode power supplies. Some power supplies have a manual switch for selecting input voltage, while others automatically adapt to the mains voltage.

Important Computer Parts ExplainedPower Supply Connector

Most modern desktop personal computer power supplies conform to the ATX specification, which includes form factor and voltage tolerances. While an ATX power supply is connected to the mains supply, it always provides a 5-volt standby (5VSB) power so that the standby functions on the computer and certain peripherals are powered. ATX power supplies are turned on and off by a signal from the motherboard. They also provide a signal to the motherboard to indicate when the DC voltages are in spec, so that the computer is able to safely power up and boot.

Mouse and Keyboard Ports

The PS/2 keyboard-and-mouse ports are designed to connect your keyboard and mouse. The below figure illustrates the plug that fits in the keyboard and mouse ports. The keyboard and mouse use the same kind of ports (but don’t get them mixed up, or they won’t work).

Important Computer Parts ExplainedMouse and Keyboard Ports

Each port is typically color-coded and marked with an icon (a keyboard for the keyboard and a mouse for the mouse — nothing confusing there) to indicate which piece of hardware gets connected where.

Virtually all PC hardware manufacturers are turning to USB keyboards and USB mice. (Which is why USB is so important to the modern PC.) You don’t get any real advantage from using a USB keyboard or mouse over a PS/2 keyboard or mouse because you don’t really have to configure a PS/2 connection, and you’re not continually unplugging and reconnecting your keyboard and mouse.

DIP (Dual In-Line Package) Switch

A dual inline package switch (DIP switch) is a set of manual electrical switches designed to hold configurations and select the interrupt request (IRQ). DIP switches are used in place of jumper blocks. Most motherboards have several DIP switches or a single bank of DIP switches. Commonly, DIP switches are used to hold configuration settings.

Important Computer Parts ExplainedDIP Switch

Normally DIP switches are found on motherboards, expansion cards or auxiliary cards. They consist of tiny rectangular components that contain parallel rows of terminals (terminal pins) and a connecting mechanism to the circuit board.

Programmable chips on a computer and extra self-configuration hardware have drastically eliminated the need for DIP switches. The trend is for settings to be accessed through a software control panel, allowing for easier and more convenient changes.


In electronics and particularly computing, a jumper is a short length of conductor used to close, open or bypass part of an electronic circuit. They are typically used to set up or configure printed circuit boards (PCBs), such as the motherboards of computers.. The process of setting a jumper is often called strapping.

Important Computer Parts ExplainedJumper

Heat Sink (Cooling System)

Computer cooling is required to remove the waste heat produced by computer components, to keep components within permissible operating temperature limits. Components that are susceptible to temporary malfunction or permanent failure if overheated include integrated circuits such as central processing units (CPUs), chipsets, graphics cards, and hard disk drives.

Important Computer Parts ExplainedHeat Sink

Components are often designed to generate as little heat as possible, and computers and operating systems may be designed to reduce power consumption and consequent heating according to workload, but more heat may still be produced than can be removed without attention to cooling. Use of heatsinks cooled by airflow reduces the temperature rise produced by a given amount of heat. Attention to patterns of airflow can prevent the development of hotspots. Computer fans are widely used along with heatsink fans to reduce temperature by actively exhausting hot air. There are also more exotic cooling techniques, such as liquid cooling. All modern day processors are designed to cut out or reduce their voltage or clock speed if the internal temperature of the processor exceeds a specified limit.

Cooling may be designed to reduce the ambient temperature within the case of a computer, such as by exhausting hot air, or to cool a single component or small area (spot cooling).

Clock Generator

A clock generator is an electronic oscillator  that produces a clock signal for use in synchronizing a circuit’s operation. The signal can range from a simple symmetrical  square wave to more complex arrangements. The basic parts that all clock generators share are a resonant circuit and an amplifier.

Important Computer Parts ExplainedClock Generator

The resonant circuit is usually a quartz piezo-electric oscillator, although simpler tank circuits and even RC circuits may be used.

The amplifier circuit  usually inverts the signal from the oscillator and feeds a portion back into the oscillator to maintain oscillation.

The clock generator in a motherboard is often changed by computer enthusiasts to control the speed of their CPU, FBS, GPU and RAM.  Typically the programmable clock generator is set by the BIOS at boot time to the selected value; although some systems have dynamic frequency scaling, which frequently re-programs the clock generator.

Hard Drive

A hard disk drive (sometimes abbreviated as a hard drive, HD, or HDD) is a non-volatile data storage device.It is usually installed internally in a computer, attached directly to the disk controller of the computer’s motherboard. It contains one or more platters, housed inside of an air-sealed casing. Data is written to the platters using a magnetic head, which moves rapidly over them as they spin.

Important Computer Parts ExplainedHard Disk and Hard Disk Drive

Hard disks reside in a drive bay, connected to the motherboard using an ATA, SCSI, or SATA cable. They are powered by a connection to the computer’s PSU (power supply unit).

Examples of data stored on a computer’s hard drive include the operating system, installed software,  and the user’s personal files.

SSD (Solid State Drive)

A solid-state drive (SSD) is a solid-state storage device that uses integrated circuit assemblies to store data persistently; typically using flash memory, and functioning as secondary storage in the hierarchy of computer storage. It is also sometimes called a solid-state device or a solid-state disk, even though SSDs lack the physical spinning disks and movable read-write heads used in hard disk drives (HDDs) and floppy disks.

Important Computer Parts ExplainedSSD

Compared with electromechanical drives, SSDs are typically more resistant to physical shock, run silently, and have quicker access time and lower latency. SSDs store data in semiconductor cells.

Optical Drive DVD/RW

An optical drive is one that uses a laser to read information from optical discs such as CDs, DVDs and Blu-ray Discs. The disc rotates rapidly when inserted into the drive, and a laser beam reads the information from the disc. The DVD-RW drive in a computer is a common type of optical drive that can read and write information from and to a DVD-RW disc.

Important Computer Parts ExplainedOptical Drive

Optical drives are different from hard disk drives, which are common types of internal storage used by computers and laptops. The data in hard disk drives is stored on spinning magnetic discs that are fixed in the unit rather than being removable as with optical discs. Solid state drives perform a function similar to hard disk drives, but they accomplish the task without the need for moving parts.

PSU (Power Supply Unit)

A power supply unit (PSU) converts mains AC  to low-voltage regulated DC power for the internal components of a computer. Modern personal computers universally use switched-mode power supplies.  Some power supplies have a manual switch for selecting input voltage, while others automatically adapt to the mains voltage.

Important Computer Parts ExplainedPower Supply Unit

Most modern desktop personal computer power supplies conform to the ATX specification,  which includes form factor and voltage tolerances. While an ATX power supply is connected to the mains supply, it always provides a 5-volt standby (5VSB) power so that the standby functions on the computer and certain peripherals are powered. ATX power supplies are turned on and off by a signal from the motherboard. They also provide a signal to the motherboard to indicate when the DC voltages are in spec so that the computer is able to safely power up and boot.


A computer monitor is an output device that displays information in pictorial form. A monitor usually comprises the visual display, circuitry, casing, and power supply.  The display device in modern monitors is typically a thin film transistor liquid crystal display (TFT-LCD) with LED backlighting having replaced cold-cathode fluorescent backlighting. Previous monitors used a cathode ray tube (CRT). Monitors are connected to the computer via VGA, Digital Visual Interface (DVI), HDMI, DisplayPort, USB-C, Low-Voltage Differential Signaling (LVDS), or other proprietary connectors and signals.

Important Computer Parts ExplainedMonitor

Originally, computer monitors were used for data processing while television sets were used for entertainment. From the 1980s onwards, computers (and their monitors) have been used for both data processing and entertainment, while televisions have implemented some computer functionality. The common aspect ratio of televisions, and computer monitors, has changed from 4:3 to 16:10, to 16:9.


A keyboard is one of the primary input devices used with a computer. Similar to an electric typewriter, a keyboard is composed of buttons used to create letters, numbers, and symbols, and perform additional functions.

Important Computer Parts ExplainedKeyboard

Today, most keyboards are similar to each other, but may be missing one or more of the sections mentioned earlier (e.g., the keypad). Where keyboards begin to differ the most is in their construction and design. Some keyboards are mechanical, while others use membrane keys. Some keyboards are split down the middle, and others fold in half or roll-up. While most keyboards use the QWERTY layout, there are still designs that utilize the DVORAK layout.


A computer mouse (plural mice, rarely mouses) is a hand-held pointing device that detects two-dimensional motion relative to a surface. This motion is typically translated into the motion of a pointer on a display, which allows a smooth control of the graphical user interface of a computer.

Important Computer Parts ExplainedMouse

Mice originally used a ball rolling on a surface to detect motion, but modern mice often have optical sensors that have no moving parts. Originally wired to a computer, many modern mice are cordless, relying on short-range radio communication with the connected system.

In addition to moving a cursor, computer mice have one or more buttons to allow operations such as selection of a menu item on a display. Mice often also feature other elements, such as touch surfaces and scroll wheels, which enable additional control and dimensional input.There are many types of mouse. Optical mouse, wireless mouse, mechanical mouse, trackball mouse. For desktop computers, the mouse is placed on a flat surface such as a mouse pad or a desk and is placed in front of your computer.

Common External Peripherals


In computing, a printer is a peripheral machine that makes a persistent representation of graphics or text, usually on paper. While most output is human-readable, barcode printers are an example of expanded use for printers. The different types of printers include 3D printers, inkjet printers, laser printers, thermal printers, etc.

Important Computer Parts ExplainedPrinter


A scanner is an input device that scans documents such as photographs and pages of text. When a document is scanned, it is converted into a digital format. This creates an electronic version of the document that can be viewed and edited on a computer.

Important Computer Parts ExplainedScanner

Most scanners are flatbed devices, which means they have a flat scanning surface. This is ideal for photographs, magazines, and various documents. Most flatbed scanners have a cover that lifts up so that books and other bulky objects can also be scanned. Another type of scanner is a sheet-fed scanner, which can only accept paper documents. While sheet-fed scanners cannot scan books, some models include an automatic document feeder, which allows multiple pages to be scanned in sequence.

Scanners work in conjunction with computer software programs, which import data from the scanner. Most scanners include basic scanning software that allows the user to configure, initiate, and import scans.


Computer speakers, or multimedia speakers, are speakers for use with computers, although usually capable of other audio uses, e.g. for an MP3 player. Most such speakers have an internal amplifier and consequently require a power source, which may be by a mains power supply often via an AC adapter,  batteries, or a USB port.

Important Computer Parts ExplainedSpeakers

The signal input connector is often a 3.5 mm jack plug (usually color-coded lime green per the PC 99 standard); RCA connectors are sometimes used, and a USB port may supply both signal and power (requiring additional circuitry and only suitable for use with a computer). Battery-powered wireless Bluetooth speakers require no connections at all. Most computers have speakers of low power and quality built-in; when external speakers are connected they disable the built-in speakers.

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