What is the difference between async:false and async:true in jquery ajax?

Question

In jquery ajax there is a parameter

$.ajax({async: true, ...});

What is the difference between setting the value to true and

Answer 1

Setting it to false blocks the main thread (responsible for executing JavaScript, rendering the screen, etc) and waits for the XHR to complete.

This is almost always a terrible idea. Users don't like unresponsive UIs.