Internet and WWW

• Internet

  • Worldwide connection of interconnected networks and devices
  • Is an infrastructure
  • Send and receive emails
  • Uses IP address and transmission protocols
  • Allow online chatting
• WWW

  • Collection of information accessed via the internet
  • Collection of multimedia web pages and other information on websites
  • Uses http
  • Web resources accessed via web browser
  • Uses internet to access information from web servers
  • URL are used to specify location of web pages
• Web browsers are software that allow users to access and display web pages on their device screens.
• Web browsers use hypertext mark-up language (HTML) sent from websites and produce results on user devices
• Web Browsers:

  • Have home page
  • Store user bookmarks
  • Make use of cookies
  • Use an address bar
  • Keep history
  • Many pages can be opened at the same time
  • Data stored as cache
  • Allow user to navigate
• Uniform resource locators (URL)

  • Text addresses used to access websites
  • Protocol = http or https
  • Domain host = www
  • Domain name = website name
  • Domain type = .com
  • Path is often omitted
• Protocols:

  • http: Communication protocol, defines how communication takes place between a browser and web server
  • https: http with encryption, more secure, uses TLS to encrypt normal http requests and responses
• Domain name server (DNS) - System used to find IP addresses for a domain name given in a URL. Eliminate need for users to memorise IP addresses.
• Process of DNS

  1. User opens browser and types in URL and browser asks DNS server for IP address of the website
  2. If DNS can't find IP address, request to another DNS is sent
  3. The other DNS server finds the IP address and sends it to the original DNS which now puts this IP address and associated URL into cache/database
  4. IP address sent back to user's computer
  5. Computer sets up communication with website server and required pages are downloaded. HTML files are sent from website server to computer. Computer's browser interprets HTML and displays information
• Cookies are small files/code stored on a user's computer. Cookies are sent by a web server to the browser on a user's computer.
• Session cookie:

  • Stored temporarily
  • Once browser closes, cookie is deleted
  • Used for making online purchases/virtual shopping basket
  • Don't collect information about user
• Persistent cookie:

  • Remember user's login details
  • Stored on hard drive until expiry date
  • Remain in operation even after browser closes
  • Allow websites to remember user login details for faster login
  • Serve as memory
  • Track user's browsing habits
• Cookie process:

  1. Web server sends cookies to user's browser
  2. Data is encrypted
  3. Encrypted data is stored on browser or user's HDD/SSD
  4. When user revisits website, web server requests cookie file
  5. Browser sends cookie file to web server to automatically enter details