How computers work

Computers are arguably the most important invention for humankind since the development of agriculture 10,000 years ago. No other invention has changed the way humans work, play, and explore as dramatically as the computer. Find out about how they work on this tour.

This story was created for the Google Expeditions project by Vida Systems, now available on Google Arts & Culture.

M-PESA appThe Index Project

We can now store seemingly endless amounts of data in a very small place, use them to achieve amazing feats, and have the entire sum of humankind's knowledge available in our pockets. But how exactly do they work?

Parts of a computer

This expedition will concentrate on PCs, short for personal computers. Regardless of the brand, computers generally contain the same hardware (physical parts of the computer). 

PCs have a monitor which displays information, a mouse used to navigate, a keyboard for inputting information, and a central processing unit (CPU) which interprets data.


The motherboard is a circuit board which connects all the electrical parts of the computer together. Located on the motherboard are the computer's memory, processor, graphics card, sound card, and other essential parts. 


The monitor of the computer simply displays information, such as texts and images, almost instantly. The monitor receives instructions from the video card, located on the motherboard.


A mouse is a small device that is used to navigate a pointer displayed on the monitor. Many mice are now wireless, using radio frequency to communicate with a transmitter plugged into the computer.


Under every key on a keyboard there is an open circuit. Pressing the key closes the circuit and allows a tiny amount of electrical current to travel through. Keyboards have their own processor to interpret which key is being pressed. 


The central processing unit, also known as the “brain” of the computer, is a type of microprocessor. It interprets information coming from every part of the computer.

Hard drive

The hard drive stores information in the form of 0s and 1s. This saved information can be photos, music, documents, and even your computer's operating system and programs.

Optical drive

Some computers have an optical drive, a component which uses lasers to read and interpret data from a CD or DVD. Some of these drives can write data to CDs and DVDs also.


The CPU (Central Processing Unit) is where the computer receives information, processes data, and sends instructions. CPUs are tiny circuit boards called microprocessors.

These circuit boards contain an incredible amount of transistors, each one storing a tiny piece of information. The world around you is a stylized representation of what it looks like inside a microprocessor. 


Microprocessors contain a phenomenal amount of transistors. Some of them contain over 2 billion transistors, all located on a chip not much bigger than a postage stamp.

Decision maker

The transistors work together to make decisions based on user input. These aren’t the same as decisions that we make every day, they are yes or no decisions, which is the language the computer understands.

Arithmetic/Logic Unit

Microprocessors also perform calculations using the Arithmetic/Logic Unit, or ALU. It processes all of the arithmetic (addition, subtraction, multiplication and division) and logic operations that the CPU needs to do. 


Microprocessors are responsible for moving data from one memory location to another. This data is stored as 2 numbers: either a 1 or a 0. Stringing these numbers together in different orders is like arranging letters to form different words. 


Microprocessors are made up of silicon laid out in a specific pattern. One of the most common elements on Earth, silicon is very cheap to produce and is an excellent semiconductor.

Computer memory

All the computer’s information is stored within the computer’s memory. There are 2 types of computer memory—one that only works when the computer is on and one that stores data even when the machine is shut down. We are inside a stylized representation of a memory chip.


Information is stored in the computer’s memory as a series of numbers: either 1 or 0. Each piece of information is stored in a particular place within the memory, almost like a huge room filled with filing cabinets.


RAM stands for Random Access Memory. RAM only remembers information while the computer is on and is used for short-term storage. It is easy to change or delete this data. A typical memory chip is smaller than the size of a postage stamp, and can store billions of bytes of data!


RAM memory is considered volatile because when the computer loses power, the data stored there is lost. An advantage of volatile memory is its speed, as it accesses data fast.


ROM stands for Read Only Memory, which serves as the computer’s long-term memory storage. Considered nonvolatile memory, data stored here is difficult to modify and slower to access.


ROM holds the information which tells the computer what to do when you switch it on. Usually preprogrammed in the factory, it contains the computer's BIOS (the basic input/output system).

Input and Output

Computers receive information digitally using a special language made up of 1s and 0s. In fact the word “digital” is a word that originates in the 15th century and it means “numbers less than 10” (which is also why the word “digits” is sometimes used to describe fingers!). 


Every single piece of information the computer receives, processes, and outputs is done in the form of binary—a language which only uses the numbers 1 and 0.

On and off

The reason computers use binary is because each little transistor has 2 modes: “on,” represented by 1 and “off,” represented by 0. The billions of transistors that form a processor give it an almost infinite amount of options.


Input devices give pieces of information to the computer. These include the keyboard, the mouse, the camera, and the microphone. Joysticks and bar code scanners are also input devices.


Output devices receive information from the computer, process it,  and then display that information in a form we understand. Output devices include the computer monitor, printers, and speakers.


Humans interact with and use computers via software. Software receives information from the user and interprets the information into a format that can be read by both the computer and the user. 

Computers also run an “operating system,” which organizes, displays, and collates all the software in use on the computer. 

Operating system

This piece of software runs in the background at all times. It handles the computer’s most basic processes as well as manages the computer's memory. Most importantly it acts as an interpreter between human communication and binary language.


Software needs to be installed onto a computer. This means the information about how it runs and the operations it performs is stored onto the computer’s memory.

Types of software

Software is used to complete all sorts of tasks. Essential for people to do their jobs, software can help organize data into spreadsheets, send and receive emails, and create graphics.


Of course, computers are widely used for recreation. Any game played on the computer is based on software, whether it be installed onto the computer or played within an internet browser.


A computer communicates in binary language. It receives information from input devices such as the keyboard and mouse. Individual computers can also communicate with each other, even over long distances. A network is a group of computing devices that communicate with each other.


 The internet is the largest network in the world. Researchers estimate there will be 30 billion devices connected to this network by 2020, and not just computers and cell phones. 


Home networks are connected to each other through a device called a router. A household may have tablets, cell phones, and PCs that can all print wirelessly to a printer. This communication is facilitated by the router.


The modem serves as the bridge between the home network and the internet. It connects to the cable, telephone, or satellite and the router. Many times the modem and router are combined on the same device. 


Bluetooth works by transmitting radio waves. This allows devices located physically close to each other to communicate, without cables or wires. Popular devices include headsets, smartphones, and portable speakers.

Credits: All media
The story featured may in some cases have been created by an independent third party and may not always represent the views of the institutions, listed below, who have supplied the content.
Explore more
Google apps