cream, chocolate syrup, vanilla, and milk in a blender, imagine the impossibility of trying to extract the vanilla from the milkshake after it’s been blended. This no-win backward mobility is the futile attempt to mine useful information from HTML documents. In other words: Yes, the shake tastes great, but don’t try to use the raw mate- rials again for a different purpose. XML to the rescue Developed as a response to the information-blender effect of HTML, XML is simply a practical way to work with structured information on the Web. The motivation of its inventors was to assemble structured data into something that was similar to HTML — so that data could be easily readable by people like you and me — but different enough from HTML so that it’s freely expand- able to effectively describe the data that it contains. Whether you realize it or not, almost all the information used on the Web has a natural structure or organization to it and thus can be expressed using XML. Some everyday examples include: The contents of a letter <letter> <date>March 31, 2002</date> <salutation>Dear Sir:</salutation> <text>Thanks for your recent article on Swiss Cheese chips. However, I don’t think you gave enough credit to the farmer who invented the Swiss Cheese chip - Charley Cowley.</text> <closing>Warm Regards,</closing> <signature>Mrs. Charlie Cowley</signature> </letter> Dialogue from a movie <dialogue> <rick>I’m saying it because it’s true. Inside of us, we both know you belong with Victor. You’re part of his work, the thing that keeps him going. If that plane leaves the ground and you’re not with him, you’ll regret it. Maybe not today. Maybe not tomorrow, but soon and for the rest of your life.</rick> <ilsa>But what about us?</ilsa> <rick>We’ll always have Paris. We didn’t have, we, we lost it until you came to Casablanca. We got it back last night.</rick> 10 Part I:  Getting Started with XSLT