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
- Browser interprets/renders the 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