IGCSE Computer Science 0478 — 5.1 The Internet and the World Wide Web Hangman

The 41 key terms

1network

A group of digital systems connected together so they can share data, files, printers and an internet connection. Each connected device is called a node.

2internet

The global network of networks that connects computers worldwide. The World Wide Web is one service that runs on it, alongside email, streaming and online games.

3website

A collection of linked web pages stored on web servers. A web page is a single document viewed in a browser, and the web is made up of many websites.

4hypertext

Text that contains hyperlinks. Clicking a link takes you to another web page or file. Links join pages together, which is why the web is called a web.

5client-server

A client, like your browser, sends a request for data and a server stores that data and sends a response back.

6protocol

An agreed set of rules that devices follow so they can communicate, like HTTP for web pages. Both devices must use the same protocol to understand each other.

7URL

Uniform Resource Locator: a text-based address that identifies a unique web page or file, typed into the browser address bar. It is the address, not the page content.

8https://

The protocol at the start of a URL. It tells the browser which set of rules to use to fetch the page: http:// is unencrypted, https:// is secure. The :// separates it from the rest.

9www.example.com

The human-readable name of a website's host in a URL, made of the www prefix and a top-level domain like .com or .org. It is easier to remember than a number.

10/products/shoes.html

The last part of a URL. It names the web page or file wanted: folders (the path) then the file name, like shoes.html. With no file name, the server sends a default page.

11https://www.example.com/shop/index.html

A URL splits into protocol (https), domain name (www.example.com) and web page or file name (shop/index.html). Each part can be labelled.

12HTTP

Hypertext Transfer Protocol: the set of rules a browser and web server use to request and send web pages. It is the default protocol for the web and is used only for web pages.

13HTTP request and response

The browser sends an HTTP request asking for a page. The web server sends back an HTTP response with the page's HTML, or an error such as 404 page not found.

14Encryption

Turning a readable message into a scrambled, unreadable message using a key, so it can only be read again with decryption.

15HTTPS

A secure way for your browser to talk to a website. It encrypts the data you send and receive, and shows https:// and a padlock in the address bar. A padlock does not prove a site is trustworthy.

17web browser

Software that requests web pages from web servers and displays them to the user, e.g. Chrome, Firefox, Safari or Edge. It is the client, and it is not a search engine.

18HTML

The language that defines the structure and content of a webpage using tags and elements, not appearance.

19address bar

The part of a browser where the user types a URL to visit a page. It also shows the URL of the current page and a padlock when the site is secure.

20bookmark

A saved URL (also called a favourite) in a web browser that lets the user return quickly to a web page without typing its address again.

21browser history

A list of the URLs of web pages a user has visited, usually with dates, so they can find a page again. The user can clear it.

22multiple tabs

A browser feature that keeps several web pages open at once in one window, so you can open a new tab and switch between pages without losing your place.

23navigation tools

Browser buttons such as back, forward, refresh and home that let the user move between web pages, reload the current page and return to a starting page.

24cookie

A small file a website sends to your browser. The browser stores it on your device and sends it back to that website on later visits. Browser settings can block or delete it.

25browser function

A browser tool that meets a user need: bookmarks return to a favourite site, tabs open many pages at once, history finds an old page, back goes one page.

26IP address

A unique number that identifies a device on a network, like a postal address, so data knows where to go. IPv4 looks like 192.168.1.5.

27domain name

An easy-to-remember name, like example.com, that stands in for a numeric IP address. It must be converted into the IP address before the computer can find the web server.

28DNS

Domain name server: stores a list of domain names with their matching IP addresses. Give it a domain name and it returns the IP address. Many DNS servers exist across the internet.

29DNS lookup

The browser sends a domain name to a DNS server, which searches for it and returns the matching IP address. If it has no match, it passes the request to another DNS server.

30web server

A computer that stores website files and sends them to a browser (the client) over the internet using HTTP when the browser asks for a page. It is always switched on and connected.

31HTTP request

A message the browser sends to the web server's IP address asking for a page; the server replies with the page's HTML, or an error such as 404 if it does not exist.

32rendering

Rendering is when the browser reads the HTML it received and paints it into the visible page shown on screen.

33URL -> DNS -> IP -> server -> HTML -> render

The ordered steps after you enter a URL: the browser asks DNS for the IP address, sends a request to the web server, gets HTML back, then renders the page.

35session cookie

A cookie stored temporarily in memory while you browse. It has no expiry date, lasts only for one visit and is deleted when the browser is closed.

36persistent cookie

A cookie saved on the device until its expiry date or until the user deletes it, so it stays after the browser closes and is sent again on later visits.

37session vs persistent cookie

A session cookie is deleted when the browser closes; a persistent cookie is kept on the device until it expires. Cookies are text data, not programs.

38cookie personal details

A cookie can save personal details like your name or address, so forms are autofilled and you are greeted by name on later visits. A persistent cookie suits this.

39preference cookie

A cookie that records a user's preferences and browsing habits so a site can tailor what it shows, such as language, layout, suggested products or targeted adverts.

40shopping cart cookie

A cookie that remembers which items a user has added to an online shopping cart, so the cart is not emptied as they move between pages. It can last one visit or be kept for later.

41login cookie

A small file a website saves in your browser to remember you are logged in, so you do not have to type your username and password on every page.

42session or persistent

Decide how long a cookie must last: session if it can go when the browser closes, persistent if it must last for later visits. Justify your choice with because.

43full-mark answer

An exam answer that uses correct terms (URL, DNS, HTTP), gives each step in order and explains why, e.g. DNS finds the IP address so the browser knows which server to ask.