AJAX (Asynchronous Javascript and XML)

Imagine an email webpage. Wouldn't it be a pain in the ass to have to reload the page whenever we want to check for a new email? Reloading all of the HTML, CSS, JavaScript and the data required for the website is a waste of bandwidth. This is where AJAX comes in.

https://learn.jquery.com/ajax/

Most JQuery applications do not use XML, despite the name of AJAX. Instead, they transport data via HTML or JSON (JavaScript Object Notation).