X in Ajax

Garrett coined the term Ajax (Asynchronous Java-Script and XML) to describe techniques used to build new kind of Web application.

While the first letters of these words map very neatly to the cool name, they aren’t very effective in describing the technologies in question.

The X for XML is particularly problematic. It implies that XML is a requirement for Ajax applications. This simply isn’t true. To be fair, the letters XML also appear in the word XMLHttpRequest (the core technology used in most Ajax implementations), but XMLHttpRequest doesn’t sound very cool.

The XMLHttpRequest object is an extension to JavaScript that allows Web pages to communicate with a server. It’s perfect for creating Ajax applications. The XMLHttpRequest object is the engine that drives Ajax, but it doesn’t exist in a vacuum.

XML, which stands for eXtensible Markup Language, is a format for describing data. Ajax applications require some kind of structured format to deliver information from the server to the client. But XML is just one option. As we’ll see later on as we explore more, there are other ways of structuring data that are equally viable for Ajax.

This is one of the important aspect to understand.