Parts of Computer and their Functions with Images

Parts of Computer and Their Functions with Diagram

In this article, we will let you know about the most important parts of computers and their functions for kids with a diagram.

However, we will also teach you relevant topics like what is a computer, a block diagram of a computer, parts of the CPU, the use of the computer, what is keyboard, hardware parts of the computer, and much more.

Block Diagram of a Computer

block diagram of computer

In the above-shown diagram, you can see a block diagram of the computer where we have input devices, output devices, and a CPU.

Input devices are the devices that are used to feed information/data in the computer for example (Keyboard, Mouse, Scanner, etc).

In the middle of the block diagram of the computer, you will see CPU is shown. CPU stands for Central Processing Unit (unit).

It is also known as the “Brain of the Computer”.

It is because it executes or processes the provided data/information as per instructions.

Following are the three main parts of CPU:-

  • Control Unit
  • Arithmetical and Logical Unit
  • Memory Unit

Output devices are the devices that are used to get the desired result from the computer for example (monitors, Printers, etc).

Also Read :- Uses of Computer

We will discuss all of the above in detail later on. Now before directly jumping on the other parts of the Computer topic let us first understand what is Computer?

What is Computer?

What is computer

A Computer is an electronic device that is made up of a combination of hardware and software.

It receives input from the user and processes it for the desired output.

These are the devices through which we provide some input and get the output within a fraction of seconds.

Hardware parts of a computer are the physical components that we can touch and see. For, example monitor, CPU, keyboard, mouse, and printers.

Software in a computer is a set of instructions or programs that tells the computer how to compute the raw data to get the desired output.

Now we have you an overview of the computer. Let’s now jump ahead on the topic and learn about the most essential parts of a computer system and its functions.

The following are the main parts of the computer that you have seen:-

  • Monitor
  • PSU
  • Memory Unit (RAM and ROM, HDD)
  • Video Card
  • Sound Card
  • Graphic Card (GPU)
  • SSD
  • Computer Case


The monitor is a screen as we have a television at our home. It is used to display data and information.

The monitor is also known as VDU (Visual Display Unit).


The output displayed on the monitor screen is also known as soft copy.

There are different types of monitors available in the market for different types of computers.

The monitor is an example of an output device of the computer.

Types of monitors

There are three main types of monitors which are as follows:-

  • CRT (Cathode Ray Tube) monitors
  • LCD (Liquid Crystal Display) monitors
  • LED (Light Emitting Diodes) monitors

CRT (Cathode Ray Tube) monitors

CRT (Cathode Ray Tube) monitors are the oldest type of monitors which occupy a lot of space on the desk.

These were heavy, bigger, and bulkier in size and consume a lot of electricity. It is rarely being used today by any organization.

LCD (Liquid Crystal Display) monitors

These monitors are lighter and compact in sizes so it occupies very less space compared to CRT monitors.

It also consumes less electricity. TFT-LCD (Thin Film Transistors- Liquid Crystal Display) generates good picture quality.

These are also known as flat-screen displays. One of the major disadvantages is that these are very high in price as compared to CRT monitors.

However, LED (Light Emitting Diode) monitors are being used widely.

LED (Light Emitting Diode) monitors

LED monitors are the latest types of monitors that come in a lot of variations of sizes like flat, curved.

These monitors consume very few amounts of electricity as compared to the LCD and CRT monitors.

The picture quality of these monitors is relatively high and they are also environmentally friendly.

If we talk about disadvantages the main one is it is very expensive as compared to the other two mentioned earlier.

CPU (Central Processing Unit)


The CPU (Central Processing Unit) is the component of a computer system, generally known as a machine’s “brain”.

The CPU is a critical part that manages all instructions and calculations that are sent to it from other computer components and peripherals.

Even the speed at which a software program runs depends very much on how powerful the CPU is functioning.

Parts of CPU

  • Memory or storage unit
  • Control unit
  • Arithmetic Logic Unit (ALU)

The main function of the CPU is to fetch, decode and execute the command given by the user for the desired output.

Memory Unit

Memory is the most important part of a computer system since the computer cannot perform basic tasks without it.

There is two kinds of memory in a computer Primary memory and Secondary memory.

The primary memory consists of RAM and ROM.

Examples of Secondary storage memory are HDD (Hard Disk Drive), CD (Compact Disk), Floppy Drive, Pen drives, etc.

Primary Memory    

Primary memory is of two types i.e. RAM and ROM. Let’s discuss them in brief.

RAM (Random Access Memory)


RAM is a computer that is a physical device that can store information temporarily. RAM is a high-speed volatile memory.

Volatile memory means a computer loses its data if the computer loses its power supply.

Data in primary memory can be stored and retried at a much faster rate than secondary memory.

That’s why primary memory is more expensive than secondary memory.

ROM (Read Only Memory)

ROM stands for Read-Only memory.  It is another type of permanent memory, where programs are stored while a computer is being created.

Unable to modify and erase stored programs in this memory, they can only be read. Therefore, this memory is called read-only memory.

Also after the device is turned off, the data contained in ROM will not be destructed. Hence, ROM is also called non-volatile memory.

The storage of programs or data is permanent in ROM. BIOS (Basic Input Output System) is also stored in ROM.

Secondary Memory

HDD (Hard Disk Drive)

hard drive

HDD is an example of secondary memory. It stores a huge amount of data permanently and it is transferred to primary as and when required by the user.

A hard disk is the most common type of secondary storage used on the computer.

External hard disks are also available in the market to increase the capacity of the data storage in a computer.

Other examples of secondary memory are Pen drives, CDs, DVDs, Floppy Drives, etc.



It is simply a flat board having a printed circuit diagram that enables the communication between the CPU, memory, and other components of the computer in addition to being the hub providing connectors for your secondary devices.

The components are connected via cables or through expansion cards.

It is also called the main circuit board, system board; baseboard, planar board, and Apple have given the term logic board for the motherboards in their brand of computer (Macintosh).

The motherboard is considered as the backbone of the computer and also a board having expansion capabilities for USBRAM slots, and few other custom components.

PSU (Power Supply Unit)

power supply unit psu

The main function of a PSU (Power Supply Unit) is to convert and regulate the AC current supply into the DC current for the various internal components of the computer system.

GPU (Graphic Processing Unit) and Graphic Card

graphic card

In simple words, a graphic card or video card is hardware in a computer that generates an output image on the screen of our monitor screen.

Sometimes it is also referred to as VPU (Visual Processing Unit).

GPU stands for Graphics Processing Unit which is also known as the brain of the graphic cards. It produces the visuals that we see on our monitor.

Good quality graphic cards produce a better image. Mostly the better graphics card is required by video editors and gamers.

Graphic cards are inserted into an expansion slot on the motherboard. Some motherboards have additional expansion slots that allow users to add an additional graphic cards.

Sound Card

sound card

A sound card is an internal component on the motherboard that is used for audio output.

Sound cards are also referred to as audio cards.

The main function of a sound card is to play the audio in the form of music provided from various sources like CDs and DVDs etc.

SSD (Solid State Drives)

solid state drive

A solid-state drive is another form of secondary storage that uses flash memory to store data. It is also one type of hard drive and relatively performs higher.

Flash memory is a memory that retains data if the electricity supply is switched off.  It is a non-volatile memory.

Flash memory is used in mobile devices, USB drives, Camera,s etc.

Computer Case

computer case

A computer case is also known as a cabinet consists of the main internal components of the computer like motherboard, CPU, graphic card, PSU, etc.

It comes in various sizes. The size and shape of the computer case are determined by the size and shape of the motherboard being used.

Examples of peripheral devices and their functions

Input Devices of a computer



Do you know what is keyboard in a computer?

A keyboard is an input device just like a typewriter with few additional keys. Generally, a standard keyboard consists of 104 keys.

It is used to feed data/information into the computer.



A mouse is an input device used to control the navigation of the cursor on a computer screen.

The mouse transforms the multi-directional movement of the hand into electronic signals, which the pointer uses to replicate its movement on the screen.

Apart from managing the cursor movement, the mouse also helps to perform other activities by clicking the buttons or scrolling the center wheel in some specified sequence or any given number of times.



In a layman’s terms, a scanner is an electronic device that can scan handwritten or printed documents and pictures and transforms them into a digital file format.

In computer terminology, it is an input device capable of scanning the images and texts on paper.

This is then converted by the scanner into a digital file (soft copy) and stored in electronic form on a computer or mobile device.

The scanned document can be viewed, shared, edited, and also take printouts on the computer.

Examples of Output Devices of a computer



A printer is an output device that generates text and graphics on a physical medium like paper.

Prints are also referred to as hard copies as the data are physically accessible and are a more permanent output type than the one displayed in the VDU (Visual Display Unit).

Printers may be divided into impact printers and non-impact printers.

An impact printer forms characters and images on a piece of paper by hitting an ink ribbon mechanism that contacts the paper physically.

A non-impact printer forms characters and graphics on a piece of paper without hitting the paper.


A projector is an output device that can take images produced by a computer and project them onto a screen or surface.

The older versions of the projectors used to create the image by shinning the light through a small transparent lens while the newer version projectors can project the image directly by using a laser.

The projectors used nowadays are known as video projectors. The projectors can produce still images or moving images.

Projectors are used in classrooms, offices, auditoriums, and also at places of worship, as it enables a group of people to watch videos, presentations, or pictures generated from a single computer.

Computer Speakers



Computer speakers are the most common output devices used with a computer. The speakers receive audio as input from the computer or a sound card then this input may be either in analog or digital form.

Most computer speakers have internal amplifiers which can increase the volume or the amplitude of the sound based on users’ requirements. 

External speakers are connected to a computer only if a user requires louder sounds, more bass, or surround sound.

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