Explainer: What is the internet?
It’s ‘a network of computers where people can share information’
The internet connects people to each other and to information. This involves a huge network of physical structures, from cables to towers to supercomputers. All sorts of devices — watches, phones, computers, appliances and more — share data using this network.
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Buzz! Your smart watch alerts you of a new social media post from a friend. She just shared a video of her dog jumping in mud. You comment: 🐶💩🤣🤣🤣
You probably don’t think at all about how that video got to you. Or consider how your emojis will get back to your friend. You and your friend could be on the same block, or on two different continents, yet the internet connects you. Almost like magic.
But the internet is not magic. The simple explanation is that the internet “is a network of computers where people can share information,” says Anne Lee. She is an expert in telecommunications at Nokia Bell Labs in Naperville, Ill. Telecommunications includes any exchange of information — also called data — over a distance.
The global internet is more than just computers, though. It’s a massive structure, with components that crisscross the globe. Cables snake below your feet. Wireless signals fly over your head. Numerous devices hide within your community. Your devices tap into this structure whenever they exchange data.
When the internet first became commonplace, people called it the “information superhighway.” Thinking about roads can really help you understand how it all works.
Cables are the roads of the internet
When your family goes on a road trip, you probably start out on smaller side streets. Then you merge onto a highway where you can travel quickly with lots of other drivers. The internet’s infrastructure is similar. Its vast network of roadlike cables direct data from far-flung places toward large central channels. Traveling data are even called “internet traffic.”
Fiber-optic cables are the roads of the internet. They contain glass filaments that carry data as bursts of light. Over 500 of these cables stretch beneath the oceans. Even more are buried underground or strung up on poles. If you could stretch out all the fiber-optic cable on Earth end-to-end, it would reach around 4 billion kilometers (2.5 billion miles). All that cable would stretch from the sun past the orbit of Uranus!
Just as roads have different numbers of lanes, these cables also come in different sizes. Bigger cables with more filaments can carry more data at once. Bandwidth is the rate of data passing through every second. The thickest cables, about the size of a garden hose, are like an interstate highway. They have the highest bandwidth.
Internet service providers (ISPs) are companies or governments that manage networks of connected cables and routers. These owners also fix these networks when they break. Verizon and AT&T are two examples of U.S.-based ISPs. Some countries provide internet service for their citizens.
Routers and exchanges are like intersections
Traveling somewhere on roads requires making lots of turns. Devices called routers exist anywhere that internet cables come together, like an intersection where roads meet. These devices direct data toward a final destination.
If the ISPs that operate different networks of cables and routers kept their systems separate, that would be a problem. It would be like having entire road systems that people couldn’t reach. To connect the entire world, ISPs have to link up.
This happens at internet exchange points (IXPs). Here, data switch from one network to another. Many IXPs are located inside ordinary buildings in towns and cities.
Data centers are like parking garages
It may seem like your friend’s silly dog video went directly from her device to yours. But that’s not usually what happens. When people share, or upload, a video or anything else to the internet, the content ends up in a building called a data center. This is like a parking garage for data.
A data center is filled with computers called servers. It also contains systems to supply electricity and keep everything cool. Videos and other content sit waiting on those servers until someone asks for them. But that’s not all servers do. They also store the programs required to run many of the apps and software that you use.
Keeping content and programs in a data center means that these files and programs are available whenever anyone wants to use them. So your devices don’t need to keep a copy of every single program or piece of content you need. And your devices can be quite small in size.
The name for this is cloud computing. You may have heard people talk about “the cloud.” It’s just another name for this huge network of gigantic buildings linked with thick cables. There’s nothing light and fluffy about it.
Wireless goes off-road
For a car to get somewhere, there generally has to be a road to follow. Internet data, though, can easily go off-road. That’s because data can travel through the air in the form of radio signals.
A home or business often has its own Wi-Fi network. In a simple home network, there’s just one router. It has an antenna that sends and receives radio signals from all the devices in the home.
If you are outside without any Wi-Fi, you can often still use the internet. You have to connect to a cellular network. This network uses tall structures called cell towers to send and receive radio signals. You can often see these towers when you’re out driving around. “They have what looks like plates at the top,” says Lee. “Those are antennas.” Cellular networks also contain smaller antennas that aren’t as easy to notice. Wi-Fi routers and cellular antennas have cables that connect them to the rest of the network.
Each cellular antenna can only reach devices located within a certain radius. 5G antennas send signals at the fastest rates. This gives people the highest internet speeds. But these signals also reach the shortest distance. In many areas, wireless antennas are spaced around 1.6 to 5 kilometers (about 1 to 3 miles) apart.
Fiber-optic cables, wireless networks and cellular networks are the most common ways that people today access the internet. But there are other ways to connect. Early internet connections used phone or electrical lines. This type of connection still exists in some places. And people in remote areas may use satellite internet.
Modems are another important part of the internet’s structure. These devices transform signals. A modem turns the bursts of light traveling through a fiber-optic cable into digital, electrical signals that a device can read, and vice versa. A modem can also transform radio waves that travel wirelessly.
A video’s internet road trip
Imagine that you just captured a pic of your cat yawning. You know your friends would love it. You tap to post it to a shared photo album. That single tap triggers a flurry of activity.
First, says Lee, “the picture itself is broken up into small pieces.” These are called packets. Each packet gets bundled with a lot of extra information, such as what the picture is and how to put its packets back together. There’s also info on how to fix any errors that might happen during the journey. And there may be a layer of encryption to keep the packet safe, so no one but the receiver can read its data.
There are also two addresses, one for the sender (you) and another for the receiver. If you’re using an Apple device, the receiver would be a server inside a data center owned by Apple. That data center may be located quite far from you.
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Your device sends these packets out into the air as radio signals. The router in your home picks up the signals. It sends them into the fiber-optic network. Now, they are traveling as bursts of light. The packets zip along through many routers and cables. They pass through internet exchange points.
The packets that make up your video may not all take the same path to their destination. When they arrive there, a server puts everything back together. It stores the picture as part of your account. When your friend goes to look at your feed, this whole process happens in reverse, says Lee.
Much of the time, this entire journey happens in a flash.
“When I was growing up, there was no internet,” says Lee. During her career, she was one of a vast team of experts who helped create the internet’s infrastructure. “It’s been actually very amazing to see that happen,” she says.
And it’s not over yet. “We’re going to go to 6G,” says Lee. “We’ll be able to support even more gaming, AR [augmented reality], VR [virtual reality], all different types of applications that people probably cannot imagine right now.” And Lee and others will continue improving the roadways of the internet to keep all our data moving where it needs to go.
