Introduction to AJAX

So, you've heard about AJAX, maybe you understand a little about how it works. But what exactly is AJAX? AJAX stands for Asynchronous JavaScript and XML, and refers to the use of JavaScript to access other documents, originally XML documents, in parallel (asynchronously) to other activities. Today, it generally involves the use of various technologies and JavaScript to get data between the server and your web browser without a page reload. All major browsers support AJAX, and it's a great way to add to the power of your website.

Why AJAX?

Generally, we use AJAX because it's the only way to fetch data from the server using JavaScript. Various other methods are available, and were used long before AJAX went mainstream, but most required the use of "hacks" and workarounds, and none were as solid and stable as AJAX. With AJAX, we can reliably fetch data from the server, submit data back to the server and maintain control over everything in between.

AJAX in the wild

AJAX is widely used around the internet; just look at the top 100 websites for some great examples of using AJAX. For example, Yahoo web search displays search term suggestions and topic meta data using AJAX, helping the user find information easier. The major web-based email clients (Gmail, Yahoo, Live Mail) are all powered by AJAX. If you are interacting with a web page, and it is fetching data without reloading the page, chances are you're using AJAX.