Ajax is a term coined by Jesse James Garrett and that became popular since the publication of the article Ajax: A New Approach to Web applications, published in February 2005, is a shortcut for Asynchronous JavaScript and XML.
The normal behavior of the Internet that involves sending pages to the browser is completely changed by the use of Ajax.
Ajax has become commonplace with its integration in HTML 5 and JavaScript frameworks, and in fact, the interest of developers has moved to HTML 5 for its new tags and APIs that accompany it.