What happens when I type
www.google.com and click go in the browser. How does the URL change to
http://www.google.com? Please explain this to me.
If no protocol is defined, the browser automatically assumes the http protocol. This may not always be the right choice though.
Lets say you have a site that needs to be accessed via the rtsp protocol at rtsp://randomsite.com
If you just type "randomsite.com" into your browser, then your browser will still go to "http://randomsite.com"