March 4, 2024

What exactly is the Internet? A computer scientist explains what it is and how it came about

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What exactly is the Internet? Nora, 8 years old, Akron, Ohio


The Internet is a global collection of computers that know how to send messages to each other. Virtually everything connected to the Internet is, in fact, a computer, or has something baked into it.

In the early 1960s, computers were used only for special purposes, such as scientific research. There weren’t many because they were big and expensive. A computer and its attached accessories could easily fill a room. To exchange data, people scheduled time to work together and one computer connected to another via a phone call.

The US government wanted a network that would allow computers to communicate automatically even if some phone lines were cut. Suppose you want to send a message from computer A to computer B on each of three different types of networks. The first is a network with a central computer connected to all the others as radios. The second is a network of several of these spoke networks with their centers connected. The third is a network where each computer is connected to several others, forming a kind of mesh. Which do you think would be more reliable if some computers and links were damaged?

Three diagrams showing many small figures connected by lines.
To send a message from A to B, which type of network is most likely to continue functioning if some lines are cut?
Txelu Balboa via Wikimedia Commons, CC BY-SA

The first network is vulnerable, because if the central computer is lost, none of the computers will be able to communicate. The second network is vulnerable because if any of the central computers are lost, the path between A and B is cut off. But in the third network, many individual computers and links could be lost and there would still be a path to connect A and B. So Therefore, the third network would be the most reliable.

hot potatoes

An American engineer named Paul Baran worked on this problem at a company called Rand Corp. In 1962, he published a new idea for computer networks, which he called “hot potato networks.”

In Baran’s idea, a message would be divided into many small pieces: potatoes. When computer A wanted to send its message to computer B, it individually sent the potatoes to a neighboring computer. That computer would get him in the right direction as soon as he could. To ensure that the messages were delivered quickly, the message fragments were treated as if they were hot, so he didn’t want them in his hands for too long.

The messages included a sequence number so that when they reached computer B, the final destination computer, that machine would know how to put them in the correct order to receive the complete message.

Baran’s idea was implemented as ARPANET. This network was the immediate predecessor of today’s Internet.

Instead of hot potatoes, the system received a more formal name, which we still use: “packet-switched networks.” The potato was renamed a package: a small part of the full message.

Vinton Cerf, an American computer scientist, is known as one of the fathers of the Internet. He contributed many essential ideas, including that the receiving computer could ask the sending computer for a packet that was lost, which they sometimes do. This is called Transmission Control Protocol or TCP.

A network of pages

Another important collaborator was Tim Berners-Lee, a British computer scientist. Berners-Lee worked at CERN, the European Organization for Nuclear Research. He wanted to create a system for his colleagues to better share the results of their research with each other.

a photograph of a man sitting in front of a cathode ray tube computer monitor
Tim Berners-Lee invented the World Wide Web in the early 1990s.
CERN, CC BY-NC

Around 1990, Berners-Lee came up with the idea that a computer could house a collection of “pages,” each of which had text, images, and links to other pages. He created a simple way to specify links on any computer: the concept of the URL or uniform resource locator.

Berners-Lee called the system the World Wide Web. He wrote the code for the first web browser to view web pages and the web server to deliver them. If you see a URL that includes “www,” it is from the original name.

Berners-Lee may have been planning to use the web particularly to share text, images and files. But earlier work on the Internet made the Web suitable for video and sound as well. YouTube, Instagram and TikTok are created using the same rules or protocols developed by Cerf and Berners-Lee.

Internet of Things

Over the past 20 years, computers have become even more powerful and affordable. Now, a computer chip that can connect directly to the Internet sells for $5, far less than today’s laptops and cell phones (about $300) or yesterday’s room-sized computers ($1 million). or more!).

a refrigerator with a water dispenser on the left door and a large screen on the right door
Many newer appliances, like this smart refrigerator, are connected to the Internet.
Paul Stefaan Mooij/Wikimedia Commons, CC BY-NC-SA

This lower cost has led to millions and millions of devices being connected to the Internet. These devices include sensors. A smart thermostat monitors your home using a temperature sensor. A security camera monitors your porch using a series of small light sensors.

These devices also include actuators, mechanisms that control activity in the physical world. For example, a smart thermostat can turn your home’s heating and cooling systems on and off.

Together, all these smart devices are called the Internet of Things or IoT. The Internet includes not only computers and phones, but all of these IoT devices. You may have a smart refrigerator that has a camera inside it. When it notices that you’re out of milk, it will send a message to your cell phone reminding you to buy more.

Almost everything is connected to the Internet now.


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