The Internet

Our show today is all about the technology that makes this app–and this podcast–possible: the Internet! Justine Sherry, a computer scientist at Carnegie Mellon University, takes us through what the Internet is and why we use it for so many things.

Guest bio: Justine Sherry

Justine Sherry

Justine Sherry is an assistant professor at Carnegie Mellon University. Her interests are in computer networking; her work includes middleboxes, networked systems, measurement, cloud computing, and congestion control. Dr. Sherry received her PhD (2016) and MS (2012) from UC Berkeley, and her BS and BA (2010) from the University of Washington. She is a recipient of the SIGCOMM doctoral dissertation award, the David J. Sakrison prize, paper awards at USENIX NSDI and ACM SIGCOMM, and an NSF Graduate Research Fellowship. Most importantly, she is always on the lookout for a great cappuccino.


ABBY: Hello and welcome to today’s edition of Name That Sound! Our first contestant is… Maggie! So Maggie, are you ready for your sound?

MAGGIE: Uh, yeah, I think so.

[noise of modem]

ABBY: All right, Maggie, name that sound!

MAGGIE: A computer?

ABBY: What’s it doing?

MAGGIE: Going crazy?  

ABBY: [laughing maniacally]

ABBY: That, my dear, that is the sound of the Internet of my childhood. It’s called a modem.

MAGGIE: What’s a modem?

ABBY: Well, we’ll get to that. When I was a child, 30ish years ago, (this is what a modem is) in order to connect to the Internet, you basically had to call in to the Internet, like pick up the phone and say “Hello internet, I would like to use you now,” using a real telephone line.

MAGGIE: That’s weird.

ABBY: And that’s the sound of the Internet connecting to your home computer via the phone line. So you weren’t just connected to the Internet all the time with wifi or cellular data or things like that. You had to actually, like, use the phone line.

MAGGIE: Hmm. Sounds annoying.

ABBY: It definitely had its annoying moments, for sure. And we used the Internet in a lot different ways back in the dark ages of the Internet. So yeah, definitely I think the Internet is better today. But the Internet is the topic for today’s episode of

MAGGIE and ABBY: Big If True!

MAGGIE: Where I, Maggie,

ABBY: And I, Abby,

Maggie: investigate the truth about big things.

MAGGIE: So here’s our quiz question for today.

ABBY: Which one of these is NOT a search engine that people have used to look for things on the Internet?

MAGGIE: A. Little River, B. Alta Vista, C. Google, or D. Lycos.

ABBY: We’ll tell you the answer near the end of the show!

ABBY: The Internet is on people’s minds a lot these days. At least here in the United States, millions of kids, including you, are using the Internet every day for school, millions of parents and teachers are working from home using Zoom or Skype or Google Meet,

MAGGIE: like me!

ABBY: Like you, and a lot of our government, social, and commercial things happen through the Internet. So have you ever wondered, what IS the Internet?

MAGGIE: I’ve wondered. The Internet feels really big—like you could use it for almost anything, and like almost everyone in the world uses it. But we wanted to find out just how big it is, and we also wanted to find out what the Internet actually is! So today we’re talking to someone who knows a lot about the Internet.

SHERRY1: My name is Justine Sherry, I am an assistant professor at Carnegie Mellon University. That means that I run a research lab where we do science and try to understand new things about the internet. And I also teach classes on the internet.

MAGGIE: Thanks for talking to us today! Before we get to how big the Internet is, will you first tell us: What IS the Internet?

SHERRY: the Internet is a network of networks, what that means is, well, we should start talking about networks. So in my house, like right here, my laptop is actually connected to a router with a cable. So that’s a wired network. We also have a wireless network in my house. So my TV and my cell phone, and all sorts of things are on the wireless network. And so like in your house or in your school, you might have a network that allows computers to talk to each other. So using the network in my house, I can have my phone tell my TV to turn up the volume or change the song that I’m listening to. And back in the day before I was even born, there were lots of networks at places like universities or businesses. But the problem was was that those networks couldn’t talk to each other. So I could use, you know, you could have a computer, at your school, talk to another computer at your school. But if you wanted to talk to somebody in another school, you couldn’t talk to them because they weren’t connected to each other. So if I were at Carnegie Mellon, my computer could talk to other computers at Carnegie Mellon. But my computer couldn’t talk to computers at other schools like MIT or the University of Washington. So the Internet was really exciting because it was a really new invention that would allow networks to talk to other networks. And so now our computers can talk to each other, even when they’re, like, in different networks on opposite sides of the globe. So today, I got a photo from of my nephew from my sister-in-law in Portugal. And I sent emails to some of my friends at the University of Washington. And we can do that because that network in my house, and the networks in Portugal and the networks in Washington are all connected to each other now.

many people connected by lines in a network

ABBY: So networks are all about different things being able to talk to each other. A network doesn’t have to just be about computers, either. You could have a network of friends, where you have three friends, and they have three friends each, and they have three friends each, and all of those people together form a network. But the networks we’re talking about are groups of computers, and then groups of groups of computers.

MAGGIE: So, when was the Internet invented?

SHERRY: a long time ago, before I was born, before your mom was born. It was invented in the 1960s. And the original design for the internet was proposed by these two researchers named Vint Cerf and Bob Kahn. Sometimes you might see Vint Cerf on TV. He works for Google now. And the first message across the internet was sent from a school called UCLA in California to another school called Stanford, which are hundreds of miles apart. And so that was sent by somebody named Leonard Kleinrock. It was really exciting. He was trying to type the word “login.” But he didn’t make it very far. It crashed after the first couple of letters. But that was the first message sent between two different networks. But it did take a long time for the Internet to become popular. So, many of the cool things that we could do with computers that can talk to other computers, we didn’t really figure out until after we had the Internet. So even though the internet was invented in the 1960s, we didn’t get email until 1971. I got my first email address in 1993 so I could write letters to my grandma. And websites weren’t invented until 1989. And Wikipedia, one of my favorite websites wasn’t invented until 2001.

MAGGIE: Who else was involved in making the Internet?

SHERRY: Vint Cerf and Bob Kahn invented, like, the original algorithms that, like, or the original protocol that allowed us to let networks talk to other networks. But there are a lot of other things that we use every day, that are also really important to what we think of as the internet that were invented by other people. So Radia Perlman invented one of the first algorithms that allowed networks to get really big, which is really important, because the internet is very big. Tim Berners-Lee invented the website, which is pretty important. You have the internet, but if you don’t have any websites, then what are you gonna do with it?

MAGGIE: So how big IS the Internet?

SHERRY: the internet is really, really, really big. This is a really fun question. I’m so glad you asked me. I did some searching before we met. Um, so I know that there are 4.6 billion people on the internet. So that’s almost two-thirds of the people in the world. I said that the Internet is a network of networks. So every network, Comcast and Verizon are networks, universities are networks, companies are networks. There are about 70,000 networks on the network on the internet. Another way to think of how big it is, is to think of like how long the cables are. So in order to connect all of those networks to the other networks, you have to run really big cables, like in between countries and in between cities, or like from your house, to the city center, and from the city center to other cities. And the longest cable in the world for the Internet is 24,000 miles long. And it goes all the way from Europe, to Japan and Australia. And the Internet even goes into space. So astronauts on the International Space Station can use the Internet to email their friends and even watch Netflix. And maybe someday when people are living on Mars, the Internet will go that far too.

MAGGIE: WOW! The Internet is huge! And it’s so cool that such a big network allows me to be able to find out so many cool things, and talk to people far away. I would love to talk to someone on the International Space Station—if you’re listening, ISS astronauts, maybe we could do an episode of Big If True using the Internet to talk to you about the ISS!

The International Space Station!

ABBY: That would be spectacular. I would love that. Since the Internet is so big, one of the key inventions that has made it more usable is the search engine, so you can find websites without knowing where they are in advance—in other words, you don’t have to know their address. Did you know that one particular search engine is used so much that people have started using its company name as a synonym for the idea of searching the Internet? Do you know which company I’m talking about?

MAGGIE: Is it Google?

ABBY: Yeah.

MAGGIE: Why is Google so everywhere?

SHERRY: There used to be a lot of search engines, you know, like when you go and search on And so like, I remember using a search engine called Lycos, there was another one called Alta Vista. But somehow Google became the best one. And everybody just started using Google all the time.

MAGGIE: Hey, there’s the answer to our quiz question: the one in our list that ISN’T a search engine is Little River.

ABBY: But you don’t HAVE to use Google to find out things if you already know where they are. Every website on the Internet has its own address, which we write in a particular way just like we write street addresses. And if you get the address wrong, you end up in the wrong place, just like if you write to 1600 Pennsylvania Street instead of 1600 Pennsylvania Avenue, your letter won’t go to the White House. On the Internet, that address has a special name: a URL. You can impress your friends by telling them that URL stands for Uniform Resource Locator.

MAGGIE: What do the different parts of a URL mean?

SHERRY: So there are two pieces to a URL. The first part of the URL is something like, or Or you could go to my website, which is And that part is really the name of the computer you want to talk to. Right. So the network’s computer networks and the internet are designed to let computers talk to other computers. And so when you send your messages, you have to give the name of the computer you want to talk to. And there’s this really big phonebook for all of the computers in the internet, called the DNS or the Domain Name System. And so if you want to give your computer a name, not all computers have names, you go and you register with the DNS. And they put a little entry in the DNS that says, here’s the name for this computer. So that’s really important, because that’s how we find each other on the internet. So that’s the first part that’s called the domain name. And then the second part of the URL the part after, like, the slashes and more slashes, that’s the file you want to get on the computer. So on your computer, you probably have a lot of files, like your homework, pictures you’ve taken, or music you like. And so these are all stored in folders on your computer, and every slash represents one folder that it’s in. So when you connect to a website over the internet, you have to tell the computer that you’re talking to what file you want to get from that computer. So all the pictures, all the words on a webpage that you’re looking at are stored in files on that computer. So if you go to, this is a real file, you can go and download it right now, is the name of the computer and dog.jpg is the name of the file. And so you can go and download that right now.

MAGGIE: Justine, thank you so much for talking to us about the Internet. One last question: What do you think is going to happen with the Internet in the future?

SHERRY:  I think the Internet is here to stay forever and won’t be an even bigger part of our lives even than it is today. I have to think that because I do work on the internet all day. So I wouldn’t work on it if I didn’t think it was important. And one way that the Internet has become a really important part of our lives now, for me is that it’s how we find information.

SHERRY: And today there are probably things that you’re used to that will be replaced by services on the Internet. So for example, you’ve probably paid for things, like at the grocery store with like, money, like, paper money, and coins, quarters and nickels and dimes. But you probably have also seen people paying for things with their watches and their phones using the Internet. And I bet you that someday you’re going to have to explain to your grandkids what a quarter is or what a nickel is; and that they won’t even know what a quarter a nickel is, because they’ll be so used to paying for things using the Internet rather than using actual paper money.

SHERRY: But what happens next is on the hands of inventors and engineers and scientists. So if you can think of it, you can invent it, then you know, we can probably make it happen.

ABBY: So now it’s your turn—tell us what you wish for the future of the Internet! You can tell us on our website,, or you can find us on Instagram or Facebook at @bigiftruepodcast. And if you reach out to us that way, you’ll already be doing an activity about our topic, since you’ll use the Internet to communicate with us! We’d love for you to tell us where you’re listening from, so then we can see how big the Big If True network is on the Internet!

MAGGIE: And we’ll see you next time when we talk about another thing that is…

MAGGIE and ABBY: Big If True!

ABBY: Special thanks to Justine Sherry for being our special guest this week. If you want to read more about her or her work, check out our shownotes, that’s at our website, Our theme and episode music are by Andrew Cote. Thanks for listening, and please tell your friends!

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