5.1 The internet and the world wide web

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The Internet and the WWW

Watch this lesson Video 5.1.1 · 7:51 · The network and what runs on it — plus how a typed address becomes a page on your screen

1. Internet vs. World Wide Web (WWW)

Many people use these terms interchangeably, but in Computer Science, they are distinct entities.

The Internet

The Hardware/Infrastructure. A massive global network of networks connected via copper wires, fiber optics, and satellites.

World Wide Web

The Service/Software. A collection of information (webpages) stored on servers, accessed via the internet using the HTTP protocol.

2. Retrieving a Webpage: HTTP, HTTPS, and Security

HTTP (Hypertext Transfer Protocol) is the set of rules used to transfer files (text, images, video) on the web.

Protocol Description
HTTP Data is sent in "Plain Text." Anyone intercepting the data can read it.
HTTPS HTTP Secure. Data is encrypted using SSL or TLS.

The Role of SSL and TLS

SSL (Secure Sockets Layer) and its successor TLS (Transport Layer Security) provide a secure link between the browser and the server.

  • They use Encryption to scramble data so hackers cannot understand it.
  • They use Certificates to authenticate that the server is who it claims to be (avoiding "spoofing").

3. The Domain Name System (DNS)

Computers communicate using IP Addresses (e.g., 192.0.2.1), but humans prefer words. The DNS acts as the "Phonebook" of the internet.

The Process:
  1. You type www.google.com into your browser.
  2. The browser sends a request to a DNS Server.
  3. The DNS looks up the IP Address for that domain.
  4. The IP address is sent back to your browser, which then contacts the server directly.

4. Anatomy of a URL

A Uniform Resource Locator is the complete web address used to find a specific resource.

https:// www.example.com /folder/ index.html
  • Protocol: How the data is sent (HTTP/HTTPS).
  • Domain Name: The name of the server/website.
  • Path: The specific folder on the server.
  • Filename: The actual web page or image file.

5. Features of a Web Browser

A browser is an application software that renders HTML code into the visual webpage you see.

Address Bar (URL Entry)
Navigation (Back/Forward)
Bookmarks/Favorites
History (Past visits)
Tabs (Multi-page viewing)
Cookies Management
⚠️ Exam Summary:

The browser requests a page using a URL. The DNS finds the IP Address. The server sends HTML files via HTTPS, which uses TLS/SSL for encryption. The browser then renders the code for the user.

Cookies

Watch this lesson Video 5.1.2 · 7:08 · Small text files a website stores on your device — what they can and cannot do

1. What are Cookies?

A Cookie is a small text file sent by a web server to a user's web browser. It is stored on the user's hard drive and contains information about the user's visit to a website.

Crucially: Cookies are not programs; they cannot carry viruses or delete files. They are just data.

2. Types of Cookies

Session Cookies

Stored in temporary memory. They are deleted as soon as the browser is closed.

Use: Keeping items in a shopping basket while you browse different pages.

Persistent Cookies

Stored on the hard drive until they reach their expiry date or are manually deleted.

Use: "Remember me" login details and user preferences (like Dark Mode).

3. Uses of Cookies

  • Personalization: Remembering your language choice or theme.
  • Authentication: Keeping you logged in as you move between pages.
  • Tracking/Analytics: Helping website owners see how many people visit and which pages are popular.
  • Targeted Advertising: Tracking your interests across different sites to show you "relevant" ads.

4. Privacy Implications

While cookies make the web easier to use, they raise significant Privacy Concerns:

  • Tracking: Third-party cookies can follow you across different websites, building a profile of your behavior without your explicit knowledge.
  • Data Sharing: Information collected by cookies can be sold to advertisers or other companies.

Side Note: The GDPR and "Cookie Banners"

The GDPR (General Data Protection Regulation) is a strict EU law that forces websites to ask for your explicit consent before using non-essential cookies.

Where did this come from? In the early 2000s, "Zombie Cookies" and invisible tracking became widespread. EU lawmakers felt that the "right to be forgotten" and the right to privacy were fundamental human rights. They wanted to stop companies from "silently" profiling citizens without their permission, leading to the "Accept All Cookies" pop-ups we see today.

⚠️ Exam Note: If asked for a benefit of cookies, mention "user convenience" (e.g., shopping baskets). If asked for a drawback, mention "invasion of privacy" or "tracking user habits."