5.1 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
  • 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

URL breakdown:

Protocol://domainhost.domain name/domain type/File Name

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

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.java script
  • 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

What is a DNS

  • Domain Name System
  • translates domain names into IP addresses

Describe how the web pages for the website 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
  • Browser interprets/renders the HTML (to display web pages)
  • Security certificates exchanged
  • Check security
  • Store/access cookies
  • Allows a homepage

Session cookies VS Persistent cookies

Session

  • stored in temporary memory on the computer
  • doesn’t actually collect any information from the user’s computer
  • doesn’t 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