In this article, you've learned how you can separate the content of your web page from the navigational elements surrounding it. The separation results in a more focused presentation of your content to search engines, as well as reduced loading time for users with low-speed Internet access, since the actual content is shown to the user before the navigational elements are downloaded.
You can implement delayed loading of the navigational elements with inline frames (IFRAME) or by using the XmlHttpRequest object implemented in most modern browsers. The IFRAME approach is supported by older browsers and thus might be the method of choice if you're concerned about backward compatibility. The usage of XmlHttpRequest object, on the other hand, gives you tighter control over the loading process and the ability to detect and handle download errors.