Asynchronous JavaScript and XML (Ajax, or AJAX) is a web development technique in which a web app fetches content from the server by making asynchronous HTTP requests, and uses the new content to update the relevant parts of the page without requiring a full page load. This can make the page more responsive, because only the parts that need to be updated are requested.

Ajax can be used to create single-page apps, in which the entire web app consists of a single document, which uses Ajax to update its content as needed.

Initially Ajax was implemented using the XMLHttpRequest interface, but the fetch() API is more suitable for modern web applications: it is more powerful, more flexible, and integrates better with fundamental web app technologies such as service workers. Modern web frameworks also provide abstractions for Ajax.

This technique is so common in modern web development that the specific term "Ajax" is rarely used.

See also