More often than not, today's Web sites more closely resemble the big black truck crawling along the freeway than the little red Ferrari zipping through traffic. Fortunately, it's not all doom and gloom. By "caching" certain sections of your Web site, you can reduce the load on your server, significantly improve application response times and make your users happier.
They get down to the basics first, talking about what caching is and what it can do to help you and your application. This is quickly followed by some sample code to get the ball rolling, showing how to cache a simple string automatically. The next obvious step is to cache the contents of an entire dynamically generated file or automatically cache an entire application (without the need to do each file independently).
There's a few other examples they include as well - caching time, partial content, results from XML requests, and how to use a database to store your cached information.