AJAX stands for Asynchronous JavaScript And XML. It’s a set of web development techniques using many web technologies to make asynchronous web applications. With AJAX, web applications can send and retrieve data from a server asynchronously without interfering with the display and behavior of the existing page. This lets you update parts of a web page, without reloading the whole page. AJAX can work with a variety of data formats, including JSON, XML, HTML, and even text files.