The interaction of Web applications such as Flickr, Backpack and Google has made a qualitative leap in this respect. This term comes from describing the transformation from a Web application based on a web page to a data-based application. In data-based applications, the data needed by users, such as contact list, can be obtained from a server independent of the actual Web page, and can be dynamically written into the web page, which renders a slow web application experience like a desktop application. Although most developers used XMLHttp or Iframe to load data in the past, until now, we have seen traditional developers and companies begin to adopt these technologies. Just as a new programming language or model is accompanied by more pain, developers need to learn new skills and how to make the best use of these new technologies.
I have a courseware PPT here. Do you want me to show you?