JMeter: Practical example of "IF Controller" and "While Controller"

Can anyone please give me a practical example of the use of "IF Controller"and "While Controller" for www.google.com

I went through the descriptions of "IF Controller" and "While Controller"but that seems unclear or confusing for starters, however, rest all controllers are understood to me.

I would like to have simple example of use of If and While Controller for www.google.com

Thanks!