🌐 The Internet and the Web

Computer Science Principles • Unit 1 • Explore Task 1 • Mr. Babb

Warm-up

They are not the same thing

People use "the Internet" and "the Web" as if they mean the same thing. They do not.

📡 The Internet

The Internet is the physical, global network of networks — billions of computers, phones, servers, routers, cables, and satellites connected together and agreeing to speak the same protocols. It was designed to be open, and it has no single owner and no central controller.

📄 The World Wide Web

The Web is one service that runs on top of the Internet: a system of linked pages and documents that you request with a browser using HTTP. Email, video calls, online games, and app updates also run on the Internet — but they are not the Web.

The analogy: the Internet is the road system. The Web is one kind of vehicle driving on it. Delivery trucks, buses, and ambulances use the same roads without being cars.

🧠 Quick check

Your friend says "the Internet went down, so my email won't send, but at least the Web still works." What is wrong with that sentence?

Simulation

Packet Race

0 messages delivered

Your message does not travel as one piece. It is chopped into numbered packets that each find their own way across the network and get reassembled at the other end. Click Send and watch.

Click any cable to cut it (and click again to repair it). Then send another message and see what the network does.

You / Server Router Cut cable Packet in flight
(the network log will appear here)

🔑 What you just saw

  • Packets: data is split into small numbered pieces, each with the sender's and receiver's addresses.
  • Routing: each router decides the next hop on its own. Packets from one message can take different paths.
  • Redundancy: there is more than one path between any two points.
  • Fault tolerance: because of that redundancy, the message still gets through when a cable is cut. That is the whole design goal of the Internet.
  • TCP reassembles packets in sequence order and re-requests any that go missing. IP handles the addressing and routing.
Match it

Who does what?

0 / 6 matched

A protocol is an agreed-on set of rules for how devices talk. No single protocol does everything — each has one job. Click a protocol, then click its job.

Trace it

How your browser finds a server

You type www.pltw.org. But computers route to IP addresses, not names. DNS — the Domain Name System — is the Internet's phone book. Step through the lookup:

Explore

Anatomy of a URL

0 / 7 found

A URL (Uniform Resource Locator) is the address of one specific resource on the Web. Every part has a job. Click each colored piece to find out what it does — find all 7.

💡 Why this matters for safety

Attackers rely on people reading URLs carelessly. The domain is the part that actually identifies the owner — and it is the piece immediately before the top-level domain, reading right to left.

https://www.pltw.org.secure-login.ru/account The real domain here is secure-login.ru — NOT pltw.org. "pltw.org" was placed in the subdomain to fool you.

Read a URL by finding the last dotted name before the first single slash. That is who you are really talking to.

Explore Task 1

Investigate a computing innovation

Choose a computing innovation that depends on the Internet — something that could not work without it. It must include a program as part of its function and it must consume, produce, or transform data.

Ideas: GPS navigation, streaming recommendation systems, contactless payment, ride-sharing dispatch, wearable health trackers, translation apps, cloud photo backup, smart thermostats, online multiplayer matchmaking, package tracking.

Your responses

Write in complete sentences. The word counter turns green when a response is developed enough. Nothing is stored — copy your work out at the bottom when you finish.

What is it, and what problem does it exist to solve?
0 words
Name the input it takes, what the program does with it, and the output it produces.
0 words
Say who benefits and how. Be specific — not "it makes life easier."
0 words
Real innovations have both. Who is disadvantaged, and how?
0 words
Name the actual data it collects or produces, then the concern that data creates.
0 words
One per line: author or publisher, title, URL, and the date you accessed it. At least one must be published in the last 12 months.
0 words

✅ Completeness check

    Exit ticket

    Show what you know

    Answer all 8 questions, then click Grade my exit ticket. One retry allowed.

    📝 Computer Science Notebook

    • The Internet is the global network of networks. The Web is one service that runs on it, using HTTP.
    • Data travels in packets: numbered pieces that each carry addressing information and may take different paths.
    • IP addresses and routes packets. TCP numbers them, reassembles them in order, and re-requests what is lost. UDP is faster but does not check.
    • DNS translates a domain name into an IP address.
    • Redundancy means more than one path exists between two points; it is what makes the Internet fault tolerant.
    • HTTPS encrypts data in transit so it cannot be read if intercepted.
    • A computing innovation includes a program and consumes, produces, or transforms data. Every one has both beneficial and harmful effects.