AJAX is a technique, not a programming language which is used by the developers to make the websites behaving like desktop applications. It operates on the client-side for creating asynchronous web applications. AJAX is a group of technologies that uses a number of web technologies for creating a set of web development techniques. 

jQuery provides various methods for AJAX functionality.

There are some jQuery AJAX methods that are used to request text, HTML, XML, or JSON from a remote server using both HTTP Get and HTTP Post. 

Complete Reference:

• jQuery | ajax() Method
• jQuery | ajaxSetup() Method
• jQuery | get() Method
• jQuery | getJSON() Method
• JQuery | parseJSON() method
• jQuery | getScript() Method
• jQuery | param() Method
• jQuery | post() Method
• jQuery | ajaxComplete() Method
• jQuery | ajaxError() Method
• jQuery | ajaxSend() Method
• jQuery | ajaxStart() Method
• jQuery | ajaxStop() Method
• jQuery | ajaxSuccess() Method
• jQuery | load() Method
• jQuery | serialize() Method
• jQuery | serializeArray() Method