Ajax is an abbreviation for Asynchronous Javascript And Xml. Ajax is just a method of retrieving data from a server and selectively changing portions of a web page without refreshing the entire page. Ajax basically uses the browser's built-in XMLHttpRequest (XHR) object to send and receive data to and from a web server asynchronously, in the background, without blocking the page or interfering with the user's experience. Ajax has grown so widespread that it is difficult to find an application that does not use it to some level. Gmail, Google Maps, Google Docs, YouTube, Facebook, Flickr, and many more large-scale Ajax-driven web services are examples. To know more information visit here https://www.phptpoint.com/ajax-tutorial/