Internet vs web
On This Lesson 11 topics
Lesson Overview
People say "the internet" and "the web" as if they were one word. They are not. The internet is the worldwide network that connects computers so they can exchange data. The web is one particular service that runs on that network: pages and apps you open in a browser. Email, video calls, online games, and file transfers also run on the internet, and none of them is the web.
This lesson draws that line clearly. It matters because every backend developer needs a correct mental map. When someone says "our service is down", you want to know whether the network is broken, the web server is broken, or a different service entirely is having trouble.
We will use the postal system as a picture throughout the module. The roads are the internet. The kinds of mail that travel on them (letters, parcels, telegrams) are the services. The web is one kind of mail, a very popular one.
This lesson builds on BEG-001, where you learned that a computer takes input, processes it, stores data, and produces output. Here we connect many computers together. You need no networking background.
Learning Objectives
By the end of this lesson you will be able to:
- Define the internet as a global network of connected computers and networks.
- Define the web as a service that runs on the internet and is used through a browser.
- Give at least three internet services that are not the web.
- Explain what a protocol is and why computers need shared ones.
- Say why a mobile app can use the internet without a browser.
- Explain why "the internet is down" and "the website is down" are different statements.
- Describe, at a high level, how data travels in small pieces called packets.
Written Explanation
What is a network?
A network is a group of computers connected so they can send data to one another. Your home might have a small one: your laptop, your phone, and your printer all talk through the same router (the box that connects your devices together and to the outside).
Networks can be connected to other networks. A company network connects to a telephone or cable provider's network, which connects to other providers, and so on. The internet is what you get when all of these networks are linked together using shared rules so that any connected device can, in principle, reach any other. The word comes from "inter-network": a network of networks.
A useful picture is the road system. No single company owns "the roads". Many organisations own pieces of them, and the pieces connect, so a letter can travel from your house to a house in another country.
What is a protocol?
Roads alone are not enough. Two computers must also agree on how to talk. A protocol is a set of rules for exchanging data: what a message looks like, who speaks first, and how to answer. Human conversation has protocols too. You say "hello", the other person says "hello", then one of you asks a question.
Different jobs use different protocols. A few you will meet:
| Protocol | What it is used for |
|---|---|
| HTTP (HyperText Transfer Protocol) and its secure form HTTPS | Fetching web pages and, increasingly, data for apps |
| SMTP (Simple Mail Transfer Protocol) | Sending email between mail servers |
| IMAP and POP | Reading email from a mailbox |
| DNS (Domain Name System) | Turning names into addresses (Lesson 3) |
The Mozilla Developer Network (MDN) lists SMTP, POP, and IMAP among the protocols that servers wait for on well-known numbered doors called ports. We return to ports in Lesson 2.
Layers: the vehicle and the cargo
The MDN article "How the web works" compares the underlying internet connection (TCP/IP) to the vehicle that carries goods, while the web's own messages (HTTP) are the goods being carried. That is a helpful way to separate the two ideas:
- The internet provides delivery: it carries small chunks of data between computers. The rules for this are called TCP/IP. You do not need the details yet. Just remember that these rules deal with getting data from one computer to another.
- The web (HTTP) defines the conversation: a browser asks for a page, a server answers.
Because delivery is separate from conversation, the same roads can carry many different conversations. That is the key to this lesson.
What is the web?
The web (short for World Wide Web) is a collection of pages, files, and applications that you reach with a URL (a web address such as https://example.com/about) and view in a browser (Chrome, Firefox, Edge, Safari). Behind each URL sits a computer called a server that sends back the content using HTTP.
Web content is built from a few kinds of files. HTML describes a page's text and structure. CSS describes how it looks. JavaScript adds behaviour. Images and videos are separate files. The browser downloads these files and assembles them into the page you see. You will study how in later modules, so for now just remember that a page is built from several downloaded pieces.
So the web is three things working together: URLs to name things, HTTP to fetch them, and browsers to display them.
Internet services that are not the web
Many everyday activities use the internet without being "the web":
- Email. When you send a message, your mail program or provider passes it to other mail servers using SMTP. You may read email in a web page (webmail), but the delivery between servers is not web traffic.
- Video calls. Calling apps send audio and video across the internet, often directly between participants or through the provider's servers.
- Online games. The game on your console talks to a game server to share positions and scores.
- File transfer and backup. Moving large files between computers, or backing up a phone, uses the internet with protocols designed for that job.
- Messaging and push notifications. Chat apps keep a connection to their servers so that new messages arrive quickly.
The simplest test is this: is it a page or app opened through a URL in a browser using HTTP? If yes, it is the web. If not, it still may be on the internet.
The blurry edge: apps and HTTP
There is one source of confusion. A mobile app (BEG-002) such as a weather or banking app often loads its data from a backend over the internet. Many backends use the same HTTP protocol that the web uses, even though the app is not a browser. So the app is using the internet, and it is using web technology, but it is not "browsing the web".
For this reason you will hear backend developers say web service or web API for a server that speaks HTTP to any client. The phrase means "a service that uses the web's protocol", not "a website". Keep this in mind: website is something you view; web service is something programs call.
How data travels: packets
A web page, an email, and a video call are all just data. To send them, the internet breaks the data into small chunks called packets. MDN describes a packet as having a header (information such as the sender's and receiver's addresses and the packet's position in the series) and a payload (the actual piece of data).
Packets can take different routes and may arrive out of order. The receiving computer uses the header information to put them back together. It is like mailing a long book as many envelopes, each numbered, so the receiver can rebuild the book.
You never see packets when you browse. They matter because they explain why the internet is robust: if one road is blocked, packets can use another.
Putting it together
The internet: roads that connect computers (TCP/IP)
+-----------------------------------------------------------+
| The web Email Video calls Games Apps |
| (HTTP in (SMTP, (real-time (game (often|
| browsers) IMAP) protocols) servers) HTTP) |
+-----------------------------------------------------------+The big box is the internet. Each smaller item inside is a service with its own protocol, and the web is just one of them.
Examples
Example 1: Is it the web? (simple)
Classify each activity.
| Activity | Uses the internet? | Is it the web? |
|---|---|---|
| Opening a news site in a browser | Yes | Yes |
| Sending an email from your mail program | Yes | No (SMTP and mail protocols) |
| Playing an online game on a console | Yes | No (game server protocol) |
| Reading webmail in a browser tab | Yes | The page you view is the web; the mail delivery behind it is not |
The last row shows that a single activity can involve both: the web page is web traffic, but the email it sends travels between mail servers using email protocols.
Example 2: One phone, three services (practical)
You sit on a train and do three things on your phone within a few minutes:
- You open a video call with a friend.
- You open a weather app that shows today's forecast.
- You open a news page in your browser.
All three need the internet connection from your mobile provider. Only the third is browsing the web. The weather app is not a browser, but it probably fetches its forecast from a backend with an HTTP request, so it uses web technology. The video call uses protocols built for real-time audio and video. If your phone loses signal, all three stop together, because they share the same roads.
Example 3: Diagnosing "it's down" (realistic)
A company runs a website and a mail system. At 9:00 a customer says, "Your internet is down."
A backend developer checks, in order:
- Can the server's network connection reach other places? (the roads)
- Is the web server program running and answering HTTP requests? (the web service)
- Is the mail server running? (a different service)
The finding: the roads are fine, email works, but the web server process crashed. The right sentence is "our website is down", not "the internet is down". The fix is to restart or repair the web server, not to call the network provider. Using the right word saves hours of looking in the wrong place.
Backend Insight
As a backend developer you will build services that live on the internet and speak one or more protocols. Today most of the backends you write will speak HTTP, so they sit on the web side of the picture. Some day you may also send email from your code or connect to a database over a different protocol.
This lesson gives you two habits:
- Name the layer. When something fails, ask whether delivery failed (network) or the conversation failed (the HTTP service). Different problems need different tools.
- Say "service", not "website". A backend serves programs as much as people. Your mobile app, another company's system, and a browser are all clients of the same backend (Lesson 4).
Later modules in this roadmap build on this map for every networking topic, from HTTP and REST through to security.
Common Mistakes
Mistake 1: Using "internet" and "web" as synonyms
- Incorrect: "Email is part of the web."
- Correct: "Email uses the internet but is not the web."
Mistake 2: Thinking an app without a browser does not use the internet
A mobile app that shows live data is almost certainly sending requests to a backend over the internet. Using no browser does not mean using no network.
Mistake 3: Believing someone owns "the internet"
The internet is many separately owned networks that agree to connect. There is no single owner and no single off switch.
Mistake 4: Saying "the internet is down" when only one service is
If a site will not load but other sites do, the roads are working. The problem is probably that one service or the network path to it.
Exercises
Try each exercise yourself before opening the solutions.
Level A: Foundation
A1. In one sentence each, define the internet and the web.
Show solution A1
A1. The internet is the global network of connected networks that lets computers exchange data. The web is a service that runs on the internet: pages and apps fetched with HTTP using URLs and shown in a browser.
A2. Name three internet services that are not the web.
Show solution A2
A2. For example email, video calls, and online games. File transfer and chat apps are also correct.
A3. What does the word protocol mean? Give one example.
Show solution A3
A3. A protocol is a set of agreed rules for exchanging data between computers. Example: HTTP for fetching web pages, or SMTP for sending email.
Level B: Application
B1. Your friend says, "I can't use the internet, my email doesn't load, but I can open news sites." What is probably wrong, and why is the friend's statement not accurate?
Show solution B1
B1. The mail service or the connection to the mail server is probably having a problem. The internet itself is working, since news sites load. Email and the web are different services using different protocols, so one can fail while the other works.
B2. A weather app on your phone shows today's forecast with no browser open. Does this use the internet? Does it use the web? Explain your answer, including what the app might be talking to.
Show solution B2
B2. It uses the internet, because the forecast arrives over the network. It likely also uses web technology, because many backends speak HTTP to apps, but it is not browsing the web in a browser. The app is probably calling a backend service, which returns the forecast data.
B3. Using the road and mail analogy, explain why one internet connection can carry web pages, email, and video calls at the same time.
Show solution B3
B3. The roads (internet) carry any kind of traffic. Web pages, email, and video calls are different kinds of mail, each with its own rules, so they can share the same roads at the same time, like letters and parcels on the same highway.
Level C: Challenge
C1. A packet-based network breaks a file into pieces. List two things that can happen to those pieces on the way, and name the information that lets the receiver rebuild the file.
Show solution C1
C1. Pieces can take different routes and can arrive out of order (some may also be lost and need resending). Each packet's header contains details such as the sender and receiver addresses and the packet's position, which lets the receiver reassemble the data in the correct order.
C2. A team says: "Our API runs on the web but is not a website." Explain what they mean and give one example of a client that is not a browser.
Show solution C2
C2. They mean the API uses the web's protocol (HTTP) but returns data for programs, not pages for people. Clients that are not browsers include a mobile app, another company's server, or a command-line tool.
Mini Challenge
Make a one-page "my day on the internet" list.
- Write down at least six things you did today that needed an internet connection (a message, a video, a map, an app update, and so on).
- For each, mark whether it was a web page in a browser, an app talking to a backend, or something else (such as a call or a game). If you are not sure, write "not sure" and make your best guess.
- Circle the items that are web and underline the items that use the internet but are not the web.
Check your work: you should have both circled and underlined items. If every item is circled, look again, because most phones run many non-browser services.
Summary & Next Lesson
Key takeaways
- The internet is the global network of connected networks. The web is one service that runs on it.
- A protocol is an agreed set of rules for exchanging data. HTTP is the web's protocol.
- Email, video calls, games, and file transfers use the internet and are not the web.
- Apps often use HTTP to talk to a backend, which is why you will hear the term web service.
- Data travels as numbered packets that the receiver reassembles.
- "The website is down" and "the internet is down" are different problems.
Next lesson
Now that you know there are roads, the next lesson asks how a computer is found on them. "IP addresses and ports" explains the street address of every connected device and the numbered doors that lead to its services.
Self-check
- Is email part of the web?
- What is a protocol?
- Name the protocol the web uses.
- Can a mobile app use the internet without a browser?
- If news sites load but your email does not, is "the internet down"?
Show answers
- No. It uses the internet but is not the web.
- A set of agreed rules for exchanging data.
- HTTP (and its secure form, HTTPS).
- Yes. Apps usually call a backend directly over the internet.
- No. The network works, so only the email service or its connection has a problem.
References
- Mozilla Developer Network, How the web works. Supports the separation of the internet connection (TCP/IP) from web content (HTTP), clients and servers, and the description of packets with a header and a payload.
- Mozilla Developer Network, Port (glossary). Lists SMTP, POP, and IMAP among the protocols with default ports. The road-and-mail analogy and the "web service" explanation are this course's own teaching additions; the definition of the internet as a network of networks is general background not taken from a specific cited page.
Practice
Apply this lesson with the module's lab, exercises and quiz.
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