Web Content: HTML, XML, CGI, JavaScript, and PHP (Webmaster in a Nutshell, 3rd Edition)

1.3. Web Content: HTML, XML, CGI, JavaScript, and PHP

While web documents can conceivably be in any format, the universal standard is Hypertext Markup Language (HTML), a language for creating formatted text interspersed with images, sounds, animation, and hypertext links to other documents anywhere on the Web. Chapter 2-Chapter 8 cover the current version of HTML.

In 1996, a significant extension to HTML was developed: Cascading Style Sheets (CSS). Cascading Style Sheets allow web site developers to associate a number of style-related characteristics (such as font, color, spacing, etc.) with a particular HTML tag. This enables HTML authors to create a consistent look and feel in a set of documents. Chapter 9 provides an overview of and a reference to CSS.

While HTML remains the widespread choice for web site development, there is an heir apparent called XML (Extensible Markup Language). XML is a meta-language that allows you to define your own document tags. Chapter 10 covers XML.

XHTML

XHTML is a more rigorous version of HTML—essentially, an XML-compliant version of HTML. As such, its syntax and tags are (mostly) the same as HTML. See Chapter 2 for more information.

When static documents aren't sufficient for a web site's needs, you can use tools such as CGI, JavaScript, mod_perl, and PHP. CGI is a way for the web server to call external programs instead of simply returning a static document. Chapter 12 through Chapter 15 are intended for CGI programmers and mod_perl programmers using the Perl programming language. JavaScript and PHP are both programming languages embedded directly into HTML documents, but that's where the similarities end: JavaScript is used primarily for client-side scripting, and PHP is used primarily for database access. See Chapter 11 and Chapter 16.