Ajax

Ajax is one of the most important emerging trends in web applications. Web sites like Google Maps and Gmail dramatically demonstrate that web applications do not have to be slow, clunky, page-at-a-time web forms. Ajax techniques can reclaim some of the fluidity and responsiveness that was lost when we moved from desktop applications to web applications.

Ajax (which stands for the cryptic "Asynchronous JavaScript and XML") is a technique for building web pages that are more interactive, exciting, and dynamic. Ajax is asynchronous: JavaScript libraries can communicate with the server at any time, and the web page need not be frozen while waiting for a response. Ajax uses JavaScript on the browser, any language on the server, and XML to specify messages.

When you use this emerging technique, a web page can communicate with the server at any time, updating only those portions of the display that need it. Users experience more responsive web pages, with immediate feedback. Even though using Ajax techniques usually requires significantly more sophisticated design and implementation skills, the benefits to the end user are so great that Ajax-enabled web applications will soon become the rule, not the exception. Fortunately, Rails makes Ajax so simple that, for typical cases, using Ajax is almost as easy as not using it.