This document provides an overview of AJAX (Asynchronous JavaScript and XML). It defines AJAX as a group of interrelated web development techniques used to create asynchronous web applications. The core components of AJAX are HTML, CSS, JavaScript, DOM and XMLHttpRequest. AJAX allows for updating parts of a web page without reloading the entire page, improving the user experience. Some benefits of AJAX include building fast, dynamic websites, improving resource sharing, and reducing server loads.