(Asynchronous Javascript And Xml) Technique for dynamically updating web pages. AJAX is the term coined in February 2005 to describe a collection of technologies used to automatically update and manipulate the information on a web page while it is being viewed in a browser (ie without the user having to manually refresh the page). This allows developers to create more sophisticated web pages and applications without having to add to the native capabilities of the browser. A key component is the use of XMLHttpRequest, a function originally added to browsers by Microsoft, to exchange data in the background with one or more web servers.