What Does Chrome Debugger Call Stack Async Option Mean?

I saw this option on the call stack header, although I am ticking it on, I don't know what does it mean, and what's the implication by ticking it on .

Solution 1:

It's useful for debugging asynchronous JavaScript. It let's you view the entire call stack and walk the stack trace for event listeners ( setInterval, setTimeout, XMLHttpRequest and others ). I've found it particularly useful for watching the value of my variables through each async call.

You can read a full description here: http://www.html5rocks.com/en/tutorials/developertools/async-call-stack/ (which is where I learned what it did a couple weeks ago!)