javascript - Why is AJAX called asynchronous?

Question

Why is AJAX called asynchronous? How does it accomplish communication asynchronously with the server?

Answer 1

It's asynchronous in that it doesn't lock up the browser. If you fire an Ajax request, the user can still work while the request is waiting for a response. When the server returns the response, a callback runs to handle it.

You can make the XMLHttpRequest synchronous if you want, and if you do, the browser locks up while the request is outstanding (so most of the time this is inappropriate)