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# AJAX Introduction * * * AJAX is a technology for updating parts of a web page without reloading the entire page. AJAX exchanges data with the server in the background and can update parts of the web page content. * * * ## Prerequisites You Should Have Before continuing, you should have a basic understanding of the following: * HTML / XHTML * CSS * JavaScript / DOM If you wish to learn these subjects first, please visit these tutorials on our ( "Novice Tutorial"). * * * ## What is AJAX? AJAX = Asynchronous JavaScript and XML. AJAX is a technology for creating fast and dynamic web pages. By exchanging a small amount of data with the server in the background, AJAX can enable asynchronous updates to web pages. This means that parts of a web page can be updated without reloading the entire page. Traditional web pages (without AJAX) must reload the entire page if they need to update content. There are many application examples using AJAX: Weibo, Taobao, Zhihu, etc. * * * ## How AJAX Works 1. **Event Trigger** (such as clicking a button or page loading). 2. **AJAX Request**: Create an `XMLHttpRequest` object via JavaScript and send a request to the server. 3. **Server Processes Request**: The server (often using PHP, Node.js, etc.) receives the request, processes it, and returns response data (JSON, XML, HTML, etc.). 4. **AJAX Response Handling**: The browser receives the response and uses JavaScript to update the content on the page without reloading the entire page.  * JavaScript/DOM (information display/interaction) * CSS (defines styles for data) * XML (as a format for transferring data) ![Image 4: lamp]( AJAX applications are browser and platform independent! * * * ## Google Suggest In 2005, Google popularized AJAX with its Google Suggest. Google Suggest uses AJAX to create a highly dynamic web interface: when you type keywords into Google's search box, JavaScript sends these characters to the server, which then returns a list of search suggestions. * * * ## Start Using AJAX Today AJAX is based on existing standards. These standards have been used by most developers for years. Read the next chapter to see how AJAX works!