XML —

Summary

Although it doesn't solve all of the world's problems, XML has a lot to offer the web community and the computing world as a whole. Not only does XML represent a path toward a cleaner and more structured HTML, it also serves as an excellent means of transporting data in a consistent format that is readily accessible across networks and different computing platforms. A variety of different XML-based languages are available for storing different kinds of information, ranging from financial transactions to mathematical equations to multimedia presentations.

This tutorial introduced you to XML and helped to explain how it came to be as well as how it fits into the future of the Web. You also learned that XML has considerable value beyond its impact on HTML. This tutorial, although admittedly not very hands on, has given you enough knowledge of XML to allow you to hit the ground running and begin creating your own XML documents in the next tutorial.

Q&A

Q.

Why isn't it possible to create custom tags in HTML, as you can in XML?
A.

HTML is a markup language that consists of a predefined set of tags that each has a special meaning to web browsers. If you were able to create custom tags in HTML, web browsers wouldn't know what to do with them. XML, on the other hand, isn't necessarily tied to web browsers, and therefore has no notion of a predefined set of tags. When you do tie an XML document to a web browser, you typically couple it with a style sheet that styles or transforms the XML data into a format more easily displayed in the browser.
Q.

Is it necessary to create a new XML-based markup language for any kind of custom data that I'd like to store?
A.

No. Although you may find that your custom data is unique enough to warrant a new markup language, you'll find that a variety of different XML-based languages are already available. In fact, most major industries have developed or are working on standardized markup languages to handle the representation of industry-specific data. OFX (Open Financial eXchange) is a good example of an industry-specific markup language that is already being used widely by the financial industry. Additionally, you may find that your XML needs are so simple that you can format data in XML without the formality of creating your own full-blown XML language.