Difference between the javascript/jQuery events “focus” and “focusin”?

Question

What is the difference between these two events: focus and focusin?

Answer 1

The focusin event is sent to an element when it, or any element inside of it, gains focus. This is distinct from the focus event in that it supports detecting the focus event on parent elements (in other words, it supports event bubbling).

http://api.jquery.com/focusin/