HTML and CSS Reference
Standard Generalized Markup Language (SGML) is a standard for specifying a markup
language or tag set. SGML in itself is not a document language, but a description of
how to specify one and create a document type definition (DTD). When Tim Berners-
Lee created HTML, he used SGML to create the specification.
HTML is the set of markup symbols or codes placed in a file intended for display on a
Web browser. The Web browser renders the code in the HTML file and displays the
Web page document and associated files. The W3C (http://www.w3.org ) sets the stan-
dards for HTML. Although the most recent version of HTML is called XHTML 1.1, this
text uses XHTML 1.0 because it is less strict and is well-supported by popular browsers.
XML was developed by the W3C as a flexible method to create common information
formats and share the format and the information on the Web. It is a text-based syntax
designed to describe, deliver, and exchange structured information. It is not intended to
replace HTML, but to extend the power of HTML by separating data from presentation.
Using XML, developers can create whatever tags they need to describe their information.
XHTML was developed by the W3C to reformulate HTML 4.01 as an application of
XML. It combines the formatting strengths of HTML 4.01 and the data structure and
extensibility strengths of XML.
The primary advantages of XHTML include the ability to extend the language by creat-
ing new tags and the promise of increased platform interoperability as mobile devices
are used more frequently to access the Web.
As this was written, the W3C's HTML Working Group (HTML WG) was busy creating
a draft recommendation for HTML 5—which is intended to be the next version of
HTML 4 and will replace XHTML. HTML 5, currently in draft status, incorporates
features of both HTML and XHTML, adds new elements, and is intended to be backward
compatible. Check the blog on the textbook's Web site, http://webdevfoundations.net,
for new developments.
1. Describe the components of the client/server model as applied to the Internet.
2. Identify two protocols used on the Internet to convey information that use the Internet
but do not use the Web.
3. Explain the similarities and differences between a URL and a domain name.