Quick Summary

• The Internet is a global network of networks (a WAN) — the infrastructure. The World Wide Web is a service that runs on it — websites and pages.
• HTTP sends data between browser and server in plain text; HTTPS does the same thing but encrypts it, which is why it's used for passwords and payments.
• A web browser is software that requests, receives, and renders (displays) web pages — plus it gives you tabs, bookmarks, history, and an address bar.
• A web server is a remote computer that stores a website's files and hands them out on request, 24/7, to many users at once.
• A URL is the text address of a page, made of three parts: protocol → domain name → file path.
• The DNS is the internet's phone book — it turns a human-friendly domain name into the numeric IP address computers actually need.
• HTML is the language that structures and presents a web page's content, built from opening/closing "tags".
• Cookies are tiny files that remember things about you. Session cookies live in RAM and vanish when you close the browser; persistent cookies live on the hard drive and survive between visits.

1. The Internet vs the World Wide Web

This is the single most commonly mixed-up idea in this whole topic, and examiners know it — so let's nail it properly, not just memorise a sentence.

What is the Internet?

• The Internet is a global network of networks — millions of smaller networks (home networks, school networks, company networks) all linked together.
• It is the most well-known example of a Wide Area Network (WAN) — a network that spans a huge geographical area, in this case the entire planet.
• Its job is to be the infrastructure — the cables, satellites, routers, and connections — that makes it possible for data to travel from one device to another anywhere in the world.

What is the World Wide Web?

• The Web (or "the web") is a collection of websites and web pages that you access using the Internet.
• It was invented in 1989 by Tim Berners-Lee, who wanted a way for people to share and access information globally.
• It's made of interconnected documents and multimedia files (text, images, video) stored on web servers all around the world, and linked together by hyperlinks.
• You access web pages through a web browser, which talks to web servers to fetch and display that content.

2. Network Protocols — HTTP & HTTPS

A protocol is simply a set of rules that devices agree to follow so they can communicate properly — a bit like two people agreeing to speak the same language and take turns talking. HTTP and HTTPS are the protocols that let your browser and a web server understand each other.

HTTP — Hypertext Transfer Protocol

• HTTP allows communication between clients (your browser) and servers (where the website lives) so you can view websites.
• It works both ways — the client can receive data from the server (e.g. fetching a webpage) and send data to the server (e.g. submitting a form, uploading a file).
• The problem: standard HTTP sends this data as plain text. If someone intercepted the traffic, they could read it directly — including passwords typed into a login form.

HTTPS — the secure version

• HTTPS works exactly like HTTP but adds an extra layer of security.
• All data sent and received using HTTPS is encrypted — scrambled into unreadable form so that even if it's intercepted, it can't be understood without the correct key.
• HTTPS is used specifically to protect sensitive information: passwords, financial/banking details, and personal data.

3. Web Browser

A web browser (Chrome, Safari, Firefox, Edge...) is a piece of software used to access and display information on the internet. Its core job is to take the raw HTML code a server sends back and render it — turn it from code into the visual page you actually see, with formatted text, images, and layout.

Functions of a web browser

4. Web Pages — How One Actually Loads

This is the section that ties everything together, and it's exactly the kind of process CIE loves to ask about in a 6–7 mark "explain how a web page is requested, sent, and displayed" question. Let's build it up piece by piece, then put it all together as one flow.

Web Servers

• A web server is a remote computer that stores the files needed to display a web page on the Internet — think of it as the "warehouse" where the website's actual content lives.
• Web servers are generally available 24/7, and their security is managed by the owner of the hardware.
• They can serve multiple users at the same time — thousands of people can request the same page simultaneously.

URLs — Uniform Resource Locators

A URL is a unique identifier for a web page — its "website address." It's text-based specifically so humans can read and remember it (compare that to remembering a string of numbers!). A URL splits into three parts:

DNS — Domain Name System

• The DNS is essentially a directory of domain names, translating human-readable domain names into numeric IP addresses.
• When you type a URL, the DNS translates the domain name into its associated IP address so your computer can connect to the server hosting the website.
• Without DNS, you'd have to memorise the IP address of every single site you wanted to visit — completely impractical.

HTML — Hypertext Markup Language

• HTML is the foundational language used to structure and present content on the web.
• It's made of elements called tags. Most tags are opened and closed, e.g. <html> ... </html>, while some are self-contained (only opened), e.g. <img> and <link>.

HTML for structure — it organises content into sections such as headers, paragraphs, and footers. The <html> tag is the root element that wraps everything else:

Other ways HTML provides structure: creating lists, positioning text on the screen, and embedding media/interactive elements.

HTML for presentation — it also displays content in a visually meaningful way, using elements like headings (<h1>, <h2>), paragraphs (<p>), links (<a>), and images (<img>). This presentation layer is mainly refined using CSS (Cascading Style Sheets). Other presentation examples: displaying data in a table, or showing images with captions.

5. Cookies

A cookie is a tiny data file stored on a computer by browser software that holds information relating to your browsing activity. Cookies typically contain:

• Browsing history — which websites you have visited
• Login information — usernames & passwords
• Preferences — language, font size, theme settings

There are two types, and the exam always wants you to compare them on the same two criteria: where they're stored, and when they're deleted.

What to Memorise

Concepts Checklist

Tick off each idea only once you can explain it out loud, without looking at your notes.

• I can explain the difference between the Internet and the World Wide Web using my own example.
• I can name at least two internet services that are not part of the web.
• I can explain what a protocol is and why HTTP and HTTPS are protocols.
• I can state the key difference between HTTP and HTTPS and why it matters.
• I can list at least four functions of a web browser.
• I can explain what a web server is and how it differs from a browser.
• I can break a URL into its three parts and explain each one.
• I can explain what DNS does and why it's needed.
• I can describe the full journey of a web page: request → DNS lookup → server → HTML → rendering.
• I understand HTML tags, and how HTML is used for both structure and presentation.
• I can explain what a cookie is and what kind of information it stores.
• I can compare session cookies and persistent cookies on storage location and deletion timing.

Exam Tips & Common Mistakes