AJAX historically stands for "Asynchronous JavaScript And XML", although XML has now more commonly been replaced by JSON (JavaScript Object Notation) encoding.

AJAX is a framework of interrelated technologies, and techniques, which enable web applications to interact with databases "in the background" (asynchronously); which means that individual parts of a web page can be updated "live", without having to refresh (reload) the entire page.

In this demo, which uses publicly available NHS data for GP practices in the UK, any one of 5 search criteria can be used to extract, and combine, information from 2 separate databases. The results, which are updated as the user continues to fill in the form, are displayed at the bottom of the page, with the search type used highlighted in red.