The Internet and the World Wide Web

Internet vs World Wide Web (WWW)

Internet

• Global connection of networks / interconnected network of computer devices
• Internet stands for Interconnected Networks
• Uses TCP/IP protocol

World Wide Web:

• Is a collection of (multimedia) web pages/documents stored on websites
• HTTP protocol used to transmit data
• Web pages are written in HTML
• URLs specify the location of the web pages
• Web documents are accessed using browsers

HTML

• Hyper Text Markup Language
• Is used in the design of web pages and to write them
• HTML is used to display content on browsers
• Web pages are written in HTML
• Web documents are accessed using browsers

URL

• Is a text-based address for a web page
• It can contain the protocol, the domain name and the web page/file name
• Format: Protocol://domainhost.domainname/domaintype/FileName

HTTPS & HTTP

HTTPS

• It is a secure protocol/hypertext transfer protocol secure
• It is a set of rules for data transmission
• It combines HTTP and SSL/TLS to transmit data
• It encrypts data for transmission

HTTP

• Hypertext transfer protocol / protocol used by web browsers
• Communication between client computers and web servers on the Internet is done by sending HTTP Requests

Web Browser & Web Server

Purpose of a web browser

• Displays web pages by rendering HTML

Functions/Features of a web browser:

• Display a web page
• Sends a request to the web server
• Receives data from a web server
• Translates HTML files
• Processes client-side scripting eg. JavaScript
• Store Favourites
• Store history
• Navigation forward and backward
• Check security
• Store/access cookies
• Allows a homepage

What is a web server?

• A server used to serve up web pages to a client
• Holds the HTML files of a web page

DNS

What is a DNS?

• Domain Name System
• Translates domain names into IP addresses

**Describe how web pages are requested and displayed on a user's

computer**

• Browser sends URL to DNS using HTTP/HTTPS
• IP address is found on DNS
• DNS returns IP address to the browser
• Browser sends request to web server/IP address
• Web server sends web pages back to browser
• Browserinterprets/rendersthe HTML (to display web pages)
• Security certificates exchanged
• Check security
• Store/access cookies

Session Cookies vs Persistent Cookies

Session

• Stored in temporary memory on the computer
• Does not actually collect any information from the user's computer
• Does not personally identify a user
• Session cookies are deleted once the browser is closed

Persistent

• Remember a user's log in details
• Stored on the hard drive of a user's computer until the expiry date is reached or the user deletes it
• Target users with advertising that matches their surfing habits
• Store user preferences