1> https://en.wikipedia.org/wiki/Ajax_%28programming%29 -
Ajax ( short for "Asynchronous JavaScript And XML) is a set of Web development techniques using many Web technologies on the client side to create asynchronous Web applications. With Ajax, Web applications can send and retrieve data from a server asynchronously (in the background) without interfering with the display and behavior of the existing page. By decoupling the data interchange layer from the presentation layer, Ajax allows Web pages to change content dynamically without the need to reload the entire page. In practice, modern implementations commonly utilize JSON instead of XML due to the advantages of JSON being native to JavaScript.
2> https://developer.mozilla.org/en-US/docs/Web/Guide/AJAX/Getting_Started
In a nutshell, it is the use of the XMLHttpRequest object to communicate with servers. It can send and receive information in various formats, including JSON, XML, HTML, and text files. AJAX’s most appealing characteristic is its "asynchronous" nature, which means it can communicate with the server, exchange data, and update the page without having to refresh the page.
The two major features of AJAX allow you to do the following:
Make requests to the server without reloading the page Receive and work with data from the server