What happen inside a computer when I press a keyboard button or click a mouse?

How Computers Work?

How Computers Work?: What happen inside a computer when I press a keyboard button or click a mouse?

Do you know what is mouse?

It’s not a rat that you might see in your home. Mouse is an input device. It is also called the pointing device. It look like a mouse that is why it is called mouse.

It is used to point to the items present on the computer screen. It has two or three buttons on top and a sensor at the button. A long wire attaches the mouse to the CPU. Nowadays wireless mouse is also available.

Friends, do you know why there is a light under the mouse. Well, the light under the mouse is the optical sensor. It detects the mouse movement. Earlier there used to be a ball inside the mouse instead of an optical sensor.

We use a mouse to select and open programs by pointing the pointer on the screen. We also use a mouse to draw a color picture on the screen.

What does the mouse consist of?

A mouse has left button, right button and a central scroll wheel.

  • The left button is used to select and click the objects on the monitor.
  • The right button helps us to perform some quick tasks with the options on the monitor
  • The central scroll wheel is used to move the cursor in any direction on the monitor

Friends, do you know that there is a correct way to hold the mouse?

  • First, position the mouse on the right side of the keyboard.
  • Place your right hands index finger on the left button of the mouse.
  • Put your right hands middle finger on the right button of the mouse.
  • Keep your palm on the back side of the mouse.

By following these steps you’ll be able to use the mouse much better.

Do you know what clicking means on a computer?

A computer mouse is used by pressing its buttons. Pressing buttons of the mouse is called clicking. Clicking means to press and release the mouse button once.

Since there are different kinds of buttons, we have different kinds of clicking.

Clicking can be done in two ways:

  • Left click: It means to press and release the left button of the mouse.
  • Right click: It means to press and release the right button of the mouse.
  • Single click: It means to press and release the mouse button once. It is used to select an object or document on the computer screen.
  • Double click: It means to press and release the mouse button twice quickly. It is used to open a file or document on the computer screen.

What is a mouse pointer?

The small moving arrow on the screen is called mouse pointer or cursor. The cursor will move in the same direction on the screen as you move the mouse on the table.

Do you know who invented the computer mouse?

The computer mouse was invented by a scientist called Douglas Engelbart. He made the first mouse by using a piece of wood. (How?)


A keyboard is a device which is used for typing in the computer. It contains many buttons on it which are called keys.

Do you know how many buttons are there on a standard keyboard?

There are 104 keys on a standard keyboard.

  • The keyboard contains 26 alphabet keys from A-Z. We can type words and sentences in the computer using the alphabet keys.
  • The number keys are also called the numeric keys. It consists of numbers from 0-9, which are the basic numbers. The numeric keys are used for typing the numbers.
  • The arrow keys are called the directional keys. They are used to move the cursor in any direction on the computer screen.
  • THE f1-f12 keys are called functional keys. They are used to perform special jobs.
  • The enter keys are located at two places on the keyboard. The enter key is used to move the cursor to the next line while typing.
  • The longest key at the bottom of the keyboard is called the spacebar key. It is used to give the blank space between letters or words while typing.
  • The Caps Lock key helps in typing the capital letters.
  • When the Numeric Key is turned ON, the number present on the numeric keypad starts working.
  • The Backspace key is used to erase the wrongly typed characters. This key is used to delete the characters or letters to the left of the cursor.
  • The Delete key is used to delete the wrong character and replace it with the correct one. The delete key erases the character on which the cursor is placed.

How Computers Work : What happen inside a computer when I click a mouse or press a key from the keyboard?

If you took your mouse apart, you will see that it is a very simple machine. It has a couple buttons and a system for detecting motion and distance. When you click a button of your mouse, it sends message to the computer with information about its position. When your mouse click is received, it’s handled by the basic subsystem.

This subsystem acts like the eyes and ears and mouth and hands of the computer.

Basically, it provides a way for the computer to interact with its environment. Similar is in the case when you press a key from the keyboard.

So when you click the mouse or press the keyboard button, the subsystem decides that your mouse click or pressing the keyboard button is important and so it sends the message to the CPU.

The CPU, or the Central Processing Unit is called the brain of the computer. Just like your brain does not take your whole body, the CPU doesn’t take up the whole computer, but it runs the show all the same. When the CPU comes to know that you have clicked the mouse or pressed the key from the keyboard, the generates an interrupt and works according to the click performed by the user i.e. the left click, right click or scroll or works according to the keys pressed from the keyboard by the user.


Also check our other amazing articles on Computers

How to Introduce Computers to Your Children

All About Internet for Kids

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Palak Gupta

Palak Gupta of the House of Ravenclaw, first of her name, loves debating, writing and coding. Fast learner. Happy and a little bit of everything different.

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