Year 11 · Computer Science · Autumn 2
The internet and its uses · Lesson 1 of 5
Internet, web, URL, HTTP and the browser
Theory5.1 The internet and the World Wide Web
Year 11 · Computer Science · The internet and its uses · Lesson 1 of 5
You will learn to
- Explain the difference between the internet and the World Wide Web.
- Identify the protocol, domain name and web page name in a URL.
- Explain the purpose of HTTP and HTTPS, and the difference between them.
- Describe how a web page is requested, found and displayed, in six numbered steps.
Year 11 · Computer Science · The internet and its uses · Lesson 1 of 5
Success criteria
You have got it when you can say:
- I can define the internet and the web in one sentence each.
- I can split any URL into its three parts.
- I can write the journey of a web request in six steps, in order.
- I can list three functions of a web browser.
Year 11 · Computer Science · The internet and its uses · Lesson 1 of 5
Retrieval starter
Questions from before. Write your answers, then show them.
- Last unit
An interpreter stops…
A At the first error it meetsB Only after translating everythingC Never
A. At the first error it meets
- Last unit
The bootloader…
A Prints documentsB Loads the operating system from storage into RAM at start-upC Translates Python
B. Loads the operating system from storage into RAM at start-up
- Last year
In 8-bit two's complement, 11111111 is…
A −1B −127C 255
A. −1
Year 11 · Computer Science · The internet and its uses · Lesson 1 of 5
Key words (1 of 3)
- Internet
- The worldwide network of connected computer networks: the physical infrastructure.
- World Wide Web (WWW)
- The collection of websites and web pages that are reached using the internet.
- URL
- Uniform resource locator: the text address of a web page, made of protocol, domain name and file name.
Year 11 · Computer Science · The internet and its uses · Lesson 1 of 5
Key words (2 of 3)
- HTTP / HTTPS
- The rules for sending web pages; HTTPS adds encryption using SSL.
- Web browser
- Application software that fetches web pages and renders HTML so you can see them.
- DNS
- Domain Name System: servers that find the IP address that matches a domain name.
- IP address
- A number that identifies a device on a network, such as 151.101.0.81.
Year 11 · Computer Science · The internet and its uses · Lesson 1 of 5
Key words (3 of 3)
- Cookie
- A small text file a website stores on your device to remember you.
- SSL
- Secure Sockets Layer: a protocol that uses certificates and encryption to secure data between browser and server.
The explanation · step 1 of 7 · part 1 of 3
The internet is not the same as the web
The internet is the physical network. It is millions of computers, cables, routers and wireless links joined together across the world. It is the infrastructure.
The World Wide Web (WWW) is a collection of websites and web pages stored on computers connected to the internet.
The web is one service that uses the internet. Email, online gaming and video calls also use the internet, but they are not the web.
The explanation · step 1 of 7 · part 2 of 3
The internet is not the same as the web (continued)
| Internet | World Wide Web | |
|---|---|---|
| What it is | A global network of networks (hardware and connections) | A collection of web pages and websites (information) |
| Made of | Cables, routers, servers, wireless links | Pages written in HTML, linked by hyperlinks |
| Uses | Web, email, video calls, file transfer, online games | Viewing web pages in a browser |
| Protocols | TCP/IP and many others | HTTP and HTTPS |
The explanation · step 1 of 7 · part 3 of 3
The internet is not the same as the web (continued)
Do not use the two words as if they mean the same thing. The internet is the network. The web is the pages.
The explanation · step 2 of 7 · part 1 of 4
The parts of a URL
A URL (uniform resource locator) is the text address of a web page. It is what you type into the address bar.
Cambridge splits a URL into three parts: the protocol, the domain name and the web page/file name.
The protocol is the set of rules used to transfer the page, such as `https`. The domain name names the web server, such as `www.bbc.co.uk`. The web page/file name is the exact page or file on that server, often with a folder path before it.
The explanation · step 2 of 7 · part 2 of 4
The parts of a URL (continued)
| Part of the domain | Meaning |
|---|---|
| www | This is a web server |
| bbc | The organisation's name |
| .co.uk | Top-level part: a company in the UK (others: .com, .org, .es, .gov) |
The explanation · step 2 of 7 · part 3 of 4
The parts of a URL (continued)
The explanation · step 2 of 7 · part 4 of 4
The parts of a URL (continued)
People remember names far more easily than numbers. The URL is a human-friendly label; DNS later turns the domain name into the server's IP address.
The protocol is not "www". The protocol is the part before `://`, such as `http` or `https`.
There is something to try for this step in the IGCSE library.
The explanation · step 3 of 7 · part 1 of 2
HTTP and HTTPS
HTTP (Hypertext Transfer Protocol) is the set of rules for sending web pages between a web server and a browser.
HTTPS (Hypertext Transfer Protocol Secure) is HTTP with encryption added, using SSL/TLS. Encryption scrambles the data so that anyone who intercepts it cannot read it.
A browser shows a padlock in the address bar when HTTPS is used. You should only type passwords or card numbers on HTTPS pages.
The explanation · step 3 of 7 · part 2 of 2
HTTP and HTTPS (continued)
With plain HTTP, data travels as readable text. Someone on the same public Wi-Fi could read your password. HTTPS stops this.
HTTPS means the connection is encrypted. It does not prove the website is honest. A fake website can also use HTTPS.
The explanation · step 4 of 7 · part 1 of 2
What a web browser does
A web browser is application software that lets you find, fetch and view web pages. Examples are Chrome, Firefox, Safari and Edge.
Its main job is to render HTML: it reads the HTML code from the server and turns it into the page you see, with text, images and links.
Cambridge lists these other functions. Learn each one.
The explanation · step 4 of 7 · part 2 of 2
What a web browser does (continued)
| Browser function | What it does |
|---|---|
| Renders HTML | Turns HTML code into a visible web page |
| Bookmarks / favourites | Saves the URL of a page so you can go back to it in one click |
| History | Keeps a list of pages you have visited, with dates and times |
| Tabs | Lets you open several pages in one browser window |
| Cookies | Stores small files from websites on your device |
| Navigation tools | Back, forward, refresh/reload and home buttons; clickable hyperlinks |
| Address bar | Where you type or see the URL; often also works as a search box |
The explanation · 3 more steps
More on the lesson page
The lesson page has the rest of the explanation, step by step:
- How a web page is retrieved, step by step
- Cookies: session and persistent
- What cookies are used for
Year 11 · Computer Science · The internet and its uses · Lesson 1 of 5
Try it: Take a URL apart
Year 11 · Computer Science · The internet and its uses · Lesson 1 of 5
Quick quiz · 1 of 3
The World Wide Web is…
- A The cables and routers
- B Pages that use the internet via HTTP
- C The same thing as the internet
B. Pages that use the internet via HTTP
The internet is the network. The web is one service on it.
Year 11 · Computer Science · The internet and its uses · Lesson 1 of 5
Quick quiz · 2 of 3
DNS…
- A Turns a domain name into an IP address
- B Stores cookies
- C Encrypts the page
A. Turns a domain name into an IP address
The phone book of the internet.
Year 11 · Computer Science · The internet and its uses · Lesson 1 of 5
Quick quiz · 3 of 3
A session cookie…
- A Lasts for years
- B Is a type of virus
- C Is deleted when the browser closes
C. Is deleted when the browser closes
A persistent cookie stays. A session cookie goes with the session.
Year 11 · Computer Science · The internet and its uses · Lesson 1 of 5
Exit ticket
Answer on paper before you go. Then check.
Pharming is…
A Guessing every passwordB Being sent to a fake website even when you type the right addressC A fake email asking for a password
B. Being sent to a fake website even when you type the right address Phishing needs you to click. Pharming redirects you, often through poisoned DNS.
A DDoS attack…
A Floods a server with requests from many machinesB Encrypts your files for moneyC Guesses passwords
A. Floods a server with requests from many machines Distributed denial of service: so many requests the server cannot answer real ones.