Basics of XML
Extensible Markup Language (XML) is a new markup language that is used to store data in a structured format. A markup language provides you with a set of tags that you can use to describe and format the text in a document. Consider a situation in which you need to create a Web page, which involves deciding the structure of the page and the content to be included in the page. You can do all of this easily by using the tags of a markup language.
For example, markup languages such as HTML have a set of predetermined tags that you can use to format the text in a document. However, sometimes you will not need the elements that exist in a markup language. In such eases, you need to create your own tags. This can be achieved using XML. Therefore, XML is called a metamarkup language.
This chapter introduces the Standard Generalized Markup Language (SGML) and the markup languages derived from it, such as XML and, Hypertext Markup Language (HTML). This enables you to compare the different markup languages that are available and identify the benefits that XML provides: In addition, this chapter focuses on the various components of an XML document. These components include type definitions, tags, attributes, and comments. Using this knowledge, you will further learn to create a sample XML document. Finally, this chapter discusses namespaces and XML schemas used with XML documents.