Assessing Your Needs
Now that you know the basics of how to use AJAX, deciding whether to use it on a project will certainly be the next step. The most important thing to keep in mind is that you can't use the Back button when you're not refreshing the page. Focus on smaller sections of your project that could benefit from using this type of interaction. For instance, you could build a form that queries a script every time a user enters an input field, or even types a letter in order to provide real-time validation. You could build a drag-and-drop page that sends data to a script on the release of an item and saves the state of the page to a database. The reasons for using AJAX definitely exist and are beneficial not only to the development experience but to users; it all depends on the situation and execution.
There are also ways to work around the issues with the Back button, such as with Google Gmail, which now provides an undo for steps that you make without refreshing the page. Many more creative examples are sure to surface, which will benefit users by providing developers with ways to create unique, real-time experiences.