On February 18, 2005, Jesse James Garrett of the design firm Adaptive Path published the essay “Ajax: A New Approach to Web Applications.” The essay gave a single name, Ajax, to a set of techniques that web developers had begun using to make pages feel more like desktop applications.
Garrett explained that Ajax, short for Asynchronous JavaScript and XML, was not a new technology but a combination of established ones: HTML and CSS for presentation, the Document Object Model for dynamic interaction, XML and the XMLHttpRequest object for retrieving data, and JavaScript to tie them together. The crucial element was the ability to exchange data with the server asynchronously, in the background, so the page did not have to reload.
The essay pointed to Google Maps and Google Suggest as examples that demonstrated how responsive a web application could feel when it loaded data behind the scenes instead of forcing a full page refresh on every action. These examples made the abstract idea concrete for a wide audience of developers.
By naming the pattern, the essay turned a scattered collection of tricks into a recognized approach with a shared vocabulary. The name caught on quickly, and Ajax became one of the defining ideas of the interactive Web of the mid-2000s.