The Internet is a global collection of computers that know how to send messages to each other. Virtually everything connected to the Internet is actually a computer – or has one “baked” into it.
In the early 1960s, computers were only used for specialized purposes such as scientific research. There weren’t many of them because they were big and expensive. A computer and its attached accessories could easily fill a room. To share data, people scheduled time to work together, and one computer would connect to the other with a phone call.
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The internet is used for much more than just surfing the web. Jonathan Kirn/The Image Bank via Getty Images
The US government wanted a network that would allow computers to communicate automatically, even if some phone lines were down. Suppose you want to send a message from computer A to computer B on each of three different network types. The first is a network with a central computer connected to all the others as spokes. The second is a network of several of these hub-and-spoke networks, with their hubs connected to each other. The third is a network in which each computer is connected to several others, forming a kind of mesh. What do you think would be the most reliable if some computers and connections got damaged?
To get a message from A to B, what kind of network is most likely to keep working if some of the lines are broken? Txelu Balboa via Wikimedia Commons, CC BY-SA
The first network is vulnerable because if the central computer fails, none of the computers can communicate. The second network is vulnerable because the path between A and B is broken if one of the hub computers fails. But in the third network, many individual computers and connections could be lost and there would still be a path to connect A and B. So the third network would be the most reliable.
hot potatoes
An American engineer named Paul Baran was working on this problem at a company called Rand Corp. In 1962 he published a new idea for computer networking, which he called “Hot Potato Networking”.
In Baran’s idea, a message would be broken down into many small pieces – the potatoes. When computer A wanted to send its message to computer B, it sent the small potatoes one by one to a neighboring computer. That computer would forward it in the right direction as quickly as possible. To ensure messages were delivered quickly, the message parts were treated as if they were hot, so you don’t want them in your hands for too long.
The messages contained a sequence number, so when they got to computer B, the final destination computer, this machine would know how to put them in the right order to get the complete message.
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Baran’s idea was implemented as ARPANET. This network was the immediate predecessor of today’s Internet.
Instead of hot potatoes, the system got a more formal name that we still use: “Packet Switched Networking”. The potato has been renamed the packet – a small part of the full message.
Vinton Cerf, an American computer scientist, is considered one of the fathers of the Internet. He contributed many key ideas, including that the receiving computer could ask the sending computer about a lost packet – which they sometimes do. This is called Transmission Control Protocol or TCP.
A web of pages
Another major contributor 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 that would allow his colleagues to better share their research results with each other.
Tim Berners-Lee invented the World Wide Web in the early 1990s. CERN, CC BY-NC
Around 1990, Berners-Lee had the idea that a computer could host a collection of “pages,” each containing text, images, and links to other pages. He created a simple way for links to identify each computer – the concept of the URL or Uniform Resource Locator.
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Berners-Lee called the system the World Wide Web. He wrote the code for the first web browser to display web pages and web servers to serve them. If you see a URL that contains “www,” that’s from the original name.
Berners-Lee may have planned to use the Internet in particular to exchange texts, images and files. But earlier work on the Internet also made the Web suitable for video and sound. YouTube, Instagram and TikTok are based on the same rules or protocols developed by Cerf and Berners-Lee.
internet of things
In the last 20 years, computers have become even more powerful and cheaper. Today, a computer chip that can connect directly to the Internet costs $5—much less than today’s laptops and cell phones (around $300) or yesterday’s room-sized computers ($1 million or more! ).
This lower cost has resulted in millions and millions of devices connecting to the internet. These devices contain sensors. A smart thermostat monitors your home using a temperature sensor. A security camera keeps an eye on your porch using a series of tiny light sensors.
These devices also include actuators—mechanisms that control activities in the physical world. For example, a smart thermostat can turn the heating and cooling systems in your home on and off.
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Collectively, all of these smart devices are referred to as the Internet of Things, or IoT. The internet isn’t just computers and phones, it’s all of these IoT devices. You may have a smart fridge that has a camera in it. When it notices you’re out of milk, it sends a message to your mobile phone, reminding you to buy more.
Almost everything is now connected to the internet.
Fred Martin, Professor of Computer Science, UMass Lowell
This article was republished by The Conversation under a Creative Commons license. Read the original article.
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