wunder beta

🌐 How the Internet Actually Works

Follow your tap from screen to server and back

6
lessons
~40 min
to learn
🔬 Science
subject
Adults
level
Start the course →

What you’ll learn

  1. The journey of a tapGrasp that a single tap triggers a real, multi-step journey across many independent networks, with data split into packets.Tapping a link launches a relay race that can cross oceans and many machines in under a second. The internet isn't one machine but millions of separate networks agreeing on shared protocols. Your request travels not as a stream but as small labeled packets.
  2. Packets, not phone callsUnderstand why packet switching replaced circuit switching and how ARPANET proved the idea.Old networks used circuit switching, reserving a whole wire per conversation, which was wasteful and fragile. In the 1960s Paul Baran and Donald Davies independently invented packet switching, labeling chunks that route around trouble. ARPANET first switched it on in 1969, founding the modern internet.
  3. Addresses and the phone bookLearn how IP addresses identify devices and how DNS translates names into those addresses before any page loads.Every device has a numeric IP address that routers use to forward packets; IPv4 ran short, so the far larger IPv6 was created. DNS, invented by Paul Mockapetris in 1983, is a distributed hierarchy that translates memorable names into IP addresses. This lookup is the quiet first step of nearly every online action.
  4. Layers, TCP and UDPSee how the internet is organized into layers and how TCP and UDP make different reliability-versus-speed trade-offs.The internet is built in stacked layers, each doing one job, captured in the TCP/IP model designed by Cerf and Kahn in 1974. IP addresses and routes packets without guarantees; TCP adds reliable, ordered delivery on top. UDP skips that checking for speed, ideal for live video and games.
  5. The physical internetAppreciate that the internet is overwhelmingly physical, from fiber and routers to undersea cables and real data centers.The internet is a planet wrapped in cables, with data traveling as light through hair-thin glass. Undersea fiber-optic cables carry roughly 95 to 99 percent of intercontinental traffic, not satellites. The cloud is simply someone else's computers in real, powered, cooled data centers.
  6. Locks and trustUnderstand how HTTPS and TLS encrypt your data and verify a site's identity using public-key cryptography and certificates.HTTPS wraps web traffic in TLS encryption so intercepted packets are unreadable, and verifies you're talking to the real site. The TLS handshake uses asymmetric encryption to agree on a shared key, then switches to faster symmetric encryption. Certificates from trusted authorities prevent impostors, which is what the padlock signals.

Questions this course answers

What is the key difference between packet switching and the older circuit switching?

Circuit switching reserves a single dedicated path for an entire conversation, like an old phone call. Packet switching instead chops data into labeled packets that travel independently, possibly via different routes, and reassemble at the destination, making the network far more resilient and efficient.

What does the Domain Name System (DNS) actually do?

DNS is the internet's phone book. Machines route by numeric IP addresses, but those are hard for people to remember, so DNS translates a name like wikipedia.org into its matching IP address using a distributed hierarchy of servers.

Why might an app choose UDP instead of TCP?

TCP reliably confirms and reorders every packet, ideal for files and web pages. UDP skips handshakes and retransmissions, so it's faster and lighter. For live video or gaming, briefly dropping a lost packet beats freezing to resend it, so speed wins over perfect reliability.

How does most data travel between continents?

Despite the talk of the cloud and satellites, undersea fiber-optic cables on the seafloor carry the overwhelming majority of intercontinental traffic, commonly estimated at roughly 95 to 99 percent. Your data literally crosses oceans as pulses of light through glass.

What does the padlock and HTTPS in your browser indicate?

HTTPS uses TLS to encrypt your data so intercepted packets look like noise, and to verify via a certificate that you're talking to the genuine site, not an impostor. The padlock signals both protections, which is what makes banking and logging in safe over shared networks.

Grounded in trusted sources

  • Cerf, V. & Kahn, R., "A Protocol for Packet Network Intercommunication," IEEE Transactions on Communications, 1974 (cs.princeton.edu/courses/archive/fall06/cos561/papers/cerf74.pdf)
  • Paul Mockapetris, RFC 882/883 "Domain Names" (1983); Internet Hall of Fame inductee biography (internethalloffame.org/inductee/paul-mockapetris)
  • Cloudflare Learning Center, "What happens in a TLS handshake?" and TeleGeography submarine-cable mythbusting (cloudflare.com/learning/ssl; resources.telegeography.com)

Every Wunder lesson is built from real, reputable sources — never invented.

Related Science courses

🤖How Large Language Models Work🧠How Your Memory Really Works✈️How Airplanes Stay in the Sky✈️How Planes Fly👁️How Your Eyes Actually Work💉How Vaccines Work🤖How AI & ChatGPT Work🔭The Hubble Space Telescope

Wunder is a personalized learn-anything platform — tell it any topic and it builds a beautiful, fact-checked course in minutes, with narration, a knowledge check, and a college-style University track.

Browse more Science courses · All topics · Home

© 2026 Wunder Learning LLC · Terms & Privacy