http://www.quirksmode.org/js/events_order.html


In addition to the above article:

when element1 contains element2 and element1.addEventListener('touchStart', tStart, false) is done and element2 is touched,

(1) by bubbling up, tStart() of element1 is called and
(2) in the function tStart(event), "event.target" refers to element2, while "this" refers to element1.