1) Ajax is an idea, not an acronym

While Ajax commonly is spelled out as Asynchronous JavaScript and XML, the full name is not entirely appropriate because it oversimplifies the history of the technology and the implementation options that lie at its heart. More exactly, Ajax encompasses the idea that Web applications can be built to opt out of the typical post-wait-repeat cycle used in server-side-focused Web applications. Ajax lets Web applications move to a more responsive, continuous, but incremental style of updating. Ajax provides users a richer, more interactive way of experiencing the underlying Web application. This goodness for the user might mean that more monitoring and security oversight might be required of network professionals, as well as, potentially, server and network alterations.

2) It's really all about JavaScript

Ajax applications are written in JavaScript and usually rely on the XMLHttpRequest object for communications, which is making its way through the World Wide Web Consortium process. Because, like many Web technologies, it now is only an ad hoc industry standard, notable differences can be found in various browsers' implementations of it. It's also possible to use other data transport mechanisms — with and without widespread industry support — with Ajax applications, including traditional frame and image-cookie methods, as well as the use of binary bridges to Flash or Java.

Regardless of the transport approach used by the developer, Ajax has raised JavaScript to a more important position within a Web application than it previously held. JavaScript now is responsible for important data-collection, communication and consumption duties, so it no longer can be treated as a second-class Web technology without serious repercussions.

Developers who think the JavaScript technology is toxic can try to avoid the language by having a tool or framework generate it from some other language like Java (Google Web Toolkit, for example), or hide the code behind components or tags (such as with .Net or Ruby). At the end of the day, however, JavaScript still will be in the application. It's better to understand the language and embrace it directly, because if you are going to use Ajax, you ultimately are using lots of JavaScript.