What is the difference between jquery on with / without selector parameter and jquery delegate?

Question

I am using jquery 1.10. I want to know what the difference is between these three functions.

Which function is better and why?

What is the purpose of the del

Answer 1

.delegate()

Attach a handler to one or more events for all elements that match the selector, now or in the future, based on a specific set of root elements.

.delegate() has been superseded by the .on() method