5.1 The internet and the World Wide Web (WWW)

| Candidates should be able to: | Notes and guidance |
| ------------------------------------------------------------------------------------------------------------------------- | ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| 1 Understand the difference between the internet and the world wide web | • The internet is the infrastructure • The world wide web is the collection of websites and web pages accessed using the internet |
| 2 Understand what is meant by a uniform resource locator (URL) | • A URL is a text-based address for a web page; it can contain the protocol, the domain name and the web page/file name |
| 3 Describe the purpose and operation of hypertext transfer protocol (HTTP) and hypertext transfer protocol secure (HTTPS) | |
| 4 Explain the purpose and functions of a web browser | • The main purpose of a web browser is to render hypertext markup language (HTML) and display web pages • Functions include: – storing bookmarks and favourites – recording user history – allowing use of multiple tabs – storing cookies – providing navigation tools – providing an address bar |
| 5 Describe how web pages are located, retrieved and displayed on a device when a user enters a URL | • Including the role of: – the web browser – IP addresses – the domain name server (DNS) – the web server – HTML |
| 6 Explain what is meant by cookies and how they are used, including session cookies and persistent cookies | • Cookies are used for functions, including: – saving personal details – tracking user preferences – holding items in an online shopping cart – storing login details |
## Internet
- It is a worldwide collection of interconnected networks.
- It is a concept, not something tangible.
- It relies on a physical infrastructure (computers, devices, hardware, servers, service providers) that allows networks and individual devices to connect to other networks and devices.
## WWW
- It is a part of the internet that users can access using web browser software.
- It consists of a massive collection of web pages, all stored on web servers.

### Difference between the internet and the world wide web
- The internet is the infrastructure
- The world wide web is a collection of web pages

#### Uniform resource locators (URLs)
- Uniform resource locator
- The website's address
- User friendly version of the IP address

### Format of URL
`protocol://website address/path/file name`
The protocol is usually either http or https.
The website address is:
- domain host (www),
- domain name (website name),
- domain type (.com, .org, .net, .gov, for example),
- and sometimes country code (.uk, .de, .cy, for example).
The path is the web page, but is often omitted and it then becomes the root directory of the website (see example below).
The file name is the item on the web page. For example:
`https://www.hoddereducation.co.uk/ict`

world wide web
- the collective name for all the web pages available
cookie
- a small text file, stored by the web browser, that can store a user’s personal data
web server
- Stores web pages // receives requests from clients and returns requested web page
hypertext markup language // HTML
the language used to create a website. Example tags are `<head>` and `<body>`
hypertext transfer protocol // HTTP
a protocol that is used to request and send web pages

### how a secure connection is created using the SSL protocol
• Encrypted connection established using asymmetric encryption
•  to make any data sent meaningless
• The **web** **browser** asks the **web** **server** to identify itself by sending its digital certificate.
• The digital certificate is authenticated/validated by the **web** **browser**.
• If the certificate is authenticated, the connection is secure/the transaction can begin.
• If the certificate is not authenticated, the transaction is cancelled.
### how the SSL protocol secures the data for transmission
- It encrypts it
- Uses digital certificates
### the process of SSL and how it provides a secure connection
- SSL is a (security) protocol
- It encrypts any data that is sent
- It uses digital certificates which is sent to the user’s browser that contains the website's public key
- The digital certificate can be used to authenticate the website
- Once the certificate is authenticated, the transaction will begin

HTTPS
- Hypertext Transfer Protocol Secure
- It is a protocol that is a set of rules/standards
- Secure version of HTTP
- Secure website // secures data
- Uses TLS / SSL
- Uses encryption
### Benefits of ssl
Data if intercepted cannot be understood // Data is encrypted // Data is scrambled // uses keys to encode/decode data
## Check if the web is secure
Locked padlock 
HTTPS
View the certificate

## Process of TLS
Client/browser requests secure connection to server
Client/browser requests the server to identify itself 
Server provides a digital certificate
Client/browser validates the certificate
Client/browser send signal back to server (to begin transmission) 
A session key is generated
Encryption method is agreed // data is encrypted
## The Two Layers of TLS
Handshake (layer) 
Record (layer)
## Describe the purpose of the handshake layer
Carries out authentication of server and client 
Handles encryption algorithms / keys

## the purpose of the web browser
Displays web pages by rendering HTML
## functions of the web browser
Storing cookies
Storing bookmarks/favourites
Recording user history
Allowing use of multiple tabs
Providing navigation tools // by example
Providing an address bar
Managing protocols // by example // checking digital certificate
Send URL to DNS
Sends a request to the IP address/web server (to obtain the contents of a webpage)
Runs active script/JavaScript/client-side script
Allows files to be downloaded from website/internet

### how the web page is requested for the user
- Web browser identified as software used to **send** URL/requests or **receives** IP address/web page data
- URL/domain sent to DNS
- DNS **searches** for **matching** IP address
- If not found sent to another DNS
- IP address sent from DNS to user’s computer
- Request sent from user’s computer to **web** **server** (for web page)
- Web page/HTML data sent from web server to user’s computer

### Cookies

Cookies are small text files that are stored by a Web browser.
Session cookies are temporary text files that are deleted when the Web browser // session is closed.
Persistent cookies are permanent text files that are stored on a user’s secondary storage device until they are manually deleted or they expire.
### difference between session cookies and persistent cookies
- Session cookies are stored in memory/RAM whereas persistent cookies are stored on the hard drive/secondary storage
- When the browser is closed a session cookie is lost whereas a persistent cookie is not lost until deleted by the user/they expire

### The use of cookies
• Storing preferences // so the user does not have to select their preferences each time they visit the site
• Storing account details // so the user does not have to remember/enter their username and password each time they visit the site
• Storing recent purchases // to allow the user to quickly re-order more items
• Storing the pages visited/items selected // to display relevant adverts
• Storing shopping basket // so when the user leaves the site the items are still in their basket