Chapter 4. HTML and Its Roots


  • Standard Generalized Markup Language (SGML)

  • Document Type Definitions (DTDs)

  • Hypertext Markup Language (HTML)

  • HTML rendering


  • Discuss SGML and its place in the history of markup languages.

  • Discuss the evolution of HTML and prepare readers for XML.

  • Discuss the structure of HTML documents.

  • Discuss Cascading Style Sheets (CSS) and their role in separating markup from rendering.

One of the original cornerstones of the web is HTML – a simple markup language whose primary purpose is to enable cross-referencing of documents through hyperlinks. In this chapter, we discuss HTML and its origins as an SGML application. We cover SGML fundamentals and show how HTML is defined within the framework of SGML. We then cover selected HTML and CSS functionality. Dynamic presentation technologies (including DHTML, JavaScript, and AJAX) are covered in Chapter 8.

Our objective in this chapter is to discuss the capabilities of HTML and related technologies. In the course of our discussion we provide examples of HTML documents to illustrate selected facets of HTML as a language. We touch upon CSS and its relationship to HTML, with the goal of explaining the role of both languages in rendering documents. However, we do not intend this chapter to be an HTML tutorial nor are we aiming to convey the finer points of page design.

SGML, XML, and their applications.

Figure 4.1. SGML, XML, and their applications. ...

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