Extensible Markup Language, or XML, is a simplified version of SGML. It is currently receiving a lot of attention. XML is essentially a markup language, meaning that it uses symbols to describe its own content. It also enables you to identify and organize your information in a more accurate and flexible way. This article is the first in a four-part series that introduces you to using XML with Delphi and the DOM.
With XML, tags consist of specially defined text enclosed in angle brackets. It is extensible because it is not a fixed format, in contrast to HTML, which has predefined markers. For example, if you want text to appear italic in HTML, you place that text between <em></em> tags. Every browser knows what to do when they encounter these tags. If however, you change these tags to say, "<ems></ems>," browsers would not know what to do, since they are only programmed to recognize the "<em></em>" tags.
In contrast to this, XML does not have any predefined tags and allows you to create your own tag sets to both display and format text. All you have to do is add a (XSL) stylesheet to enable the browser to format your text. This language can therefore be read and understood on any computer platform.
An XML document is basically a plain text file. Below is an example of and XML File: