This is the first of a series of articles that will provide a relatively high-level introduction to the basic technologies that make up Web-based software applications. These "executive overview" articles will be of interest to leadership stafffrom project lead to middle managementwho are charged with leading the development or maintenance of Web-based applications for the first time. In addition, these articles will provide a foundation of "best practices" for the organization and style of source code in a Web application. Project leaders can use this information to help form the basis of better software development processes in their organizations.
Each technology covered in this series will be explored through a series of three or four articles. These articles will first introduce the subject technology in the context of a Web-based application, focusing on its purpose, role, capabilities, and limitations. Next, we will explore the relevant technology in more detail, explaining its primary elements and functionality. The final article on each technology will present a set of standard coding and style conventions aimed at improving the maintainability and reusability of Web application code.
This article kicks off an exploration of the first and most fundamental technology used in Web-based applications: HTML. HTML, the Hypertext Markup Language, is a standard for describing the structure and presentation of information via the Internet. Web developers use HTML keywords or tags to instruct the Web browser application how to format and display the content of Web pages.
The Roots of HTML
Only a few years ago, the typical "Web application" consisted entirely of a set of static Web pages written in HTML. In contrast, today's Web-based applications combine many new technologies to provide dynamic, interactive applications across the Internet. However, HTML code is still found at the core of the vast majority of Web applications. This article begin with a brief description of the origins of HTML and the role that HTML plays in Web applications.
As a markup language, the purpose of HTML is to provide a set of general rules that suggest how content should look when rendered. A markup language doesn't dictate the methods used to display the content, nor does it have foreknowledge of the target context, so this control is imprecise.
HTML is the lingua franca of the Internet. Originally, the Internet was designed as a means for distributing information across a robust, noncentralized network of computers in a time of national emergency. Reflecting the experimental nature of this medium, the early tools available for finding and viewing information across the Internet were primitive. However, as more organizations and people adopted the Internet, the need grew for easier access to resources and for a richer display of information. Publishing HTML-formatted documents on the Internet via the World Wide Web proved to be the answer to these needs.
HTML is a subset of the Standard Generalized Markup Language (SGML). SGML is an international standard (ISO 8879) published in 1986 as a format for structuring and marking up documents. HTML adopts a simplified set of SGML's structural, semantic, and formatting tags, keeping the emphasis on the content rather than on the document itself. An important addition to HTML was the inclusion of support for hypertext, which enabled authors to define a semantic network of linked information.