Beginning XML, 4th Edition

Chapter 1. What Is XML?

XML (Extensible Markup Language) is a buzzword you will see everywhere on the Internet, but it's also a rapidly maturing technology with powerful real-world applications, particularly for the management, display, and organization of data. Together with its many related technologies, which are covered in later chapters, XML is an essential technology for anyone working with data, whether publicly on the web or privately within your own organization. This chapter introduces you to some XML basics and begins to show you why learning about it is so important.

This chapter covers the following:

• The two major categories of computer file types—binary files and text files—and the advantages and disadvantages of each

• The history behind XML, including other markup languages such as SGML and HTML

• How XML documents are structured as hierarchies of information

• A brief introduction to some of the other technologies surrounding XML, which you will work with throughout the book

• A quick look at some areas where XML is useful

While there are some short examples of XML in this chapter, you aren't expected to understand what's going on just yet. The idea is simply to introduce the important concepts behind the language so that throughout the book you can see not only how to use XML, but also why it works the way it does.

Of Data, Files, and Text

XML is a technology concerned with the description and structuring of data, so before you can really delve into the concepts behind XML, you ...