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

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What exactly is the Internet?Nora, age 8, Akron, Ohio

The Internet is a global collection of computers that know how to send messages to each other. In fact, everything that is connected to the Internet is a computer — or has a computer “built into it.”

In the early 1960s, computers were used only for special purposes, such as scientific research. There are not many of them because they are big and expensive. A single computer and its accessories can easily fill a room. To exchange data, people would schedule time to work together, and one computer would connect to another by phone.

The U.S. government wanted a network where computers could communicate automatically even if certain 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 where a central computer connects to all other computers as spokes. The second is a network of several such hub-and-spoke networks connected at their hubs. The third is a network in which each computer is connected to several other computers, forming a kind of mesh structure. Which do you think is the most reliable if some computers and links are broken?

The first network is vulnerable because if the central computer is lost, then all computers cannot communicate. The second network is vulnerable because if any of the central computers were lost, the path between A and B would be severed. But in the third network, many PCs and links may be lost, but there is still a path connecting A and B. So the third network is the most reliable.

hot potato

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

In Baran’s mind, a message would be broken down into many small pieces — potatoes. When computer A wants to send a message to computer B, it individually sends the little potato to the neighbor computer. That computer will pass it in the right direction as quickly as possible. To ensure that messages are delivered quickly, message fragments are considered hot, so you don’t want them lingering in your hands for too long.

These messages contain a sequence number so when they arrive at computer B (the final destination computer), that machine will 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 direct predecessor of today’s Internet.

Instead of being a hot potato, the system got a more formal name, which we still use: “packet-switched network”. Potatoes are renamed to a packet – a small part of the full message.

American computer scientist Vinton Cerf is known as one of the fathers of the Internet. He contributed many of the basic ideas, including that the receiving computer could ask the sending computer for missing packets — which they sometimes did. Its name is Transmission Control Protocol or TCP.

web page of web page

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

Around 1990, Berners-Lee came up with the idea that a single computer could host a collection of “pages,” each with text, images, and links to other pages. He created an easy way for links to specify any computer — the concept of a URL, or Uniform Resource Locator.

Berners-Lee named 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 URLs that contain “www” – that’s from the original name.

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

internet of things

Over the past 20 years, computers have become more powerful and cheaper. Computer chips that can connect directly to the Internet now cost $5 — a lot less than today’s laptops and cell phones ($300) or yesterday’s room-sized computers ($1 million or more!).

This lower cost has resulted in millions of devices being connected to the internet. These devices include sensors. Smart thermostats use temperature sensors to monitor your home. Security cameras monitor your front porch using an array of tiny 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.

All these smart devices are collectively known as the Internet of Things or IoT. The internet doesn’t just include computers and phones, but all of these IoT devices. You probably have a smart refrigerator with a built-in camera. When it notices you’re out of milk, it sends a message to your phone reminding you to buy more.

Almost everything is connected to the internet these days.

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This article is republished from The Conversation under a Creative Commons license. Read the original article here: https://theconversation.com/what-exactly-is-the-internet-a-computer-scientist-explains-what-it-is-and-how-it-came-to-be- 198132.