Summary
The jQuery library provides a rich set of functions supporting the needs of AJAX-enabled applications, ranging from the high-level .load() method (which replaces the contents of a DOM element with an HTML fragment loaded from the server) to the low-level $.ajax() call (which allows you to control all aspects of individual HTTP requests).
jQuery can handle common data types used in AJAX responses, including HTML fragments, XML documents, JSON data structures, JavaScript code, or plain text. It supports the complete set of callback functions available with the XMLHttpRequest object (error, success, and complete callbacks), as well as page-wide AJAX-specific events that can be used to implement application-wide visual cues for the user.