6 AnswersNew Answer
AJAX allows you to send and receive data without refreshing the page. For example, if you wanted to get data from a PHP form. normally, you'd need to redirect the user to the page which would require a refresh. With AJAX, you can do this all in the background. The user wouldn't even notice.
Ankit Jaiswal You don't need CSS or XML. CSS is definitely helpful, but XML isn't needed. You can use JSON which would work better since it's native to JS.