25.1. Understanding Ajax
Before you really get started with Ajax, it's important to understand its capabilities and limitations. Only then will you know how to fit it into your web applications.
25.1.1. Ajax: The Good
The key benefit of Ajax is responsiveness. An Ajax application, when done properly, provides a better experience for the user. Even if the user can't do anything new (or do anything faster), this improved experience can make your web application seem more modern and sophisticated. If you're creating a website that's competing against other similar sites, you just might find that Ajax allows you to distinguish your work from the rest of the pack.
Ajax can also provide genuinely new features that aren't possible in traditional web ...