Hypertext Markup Language

Hypertext Markup Language

1. History of HTML

   • Hypertext systems were envisioned as early as 1940 by Vannevar Bush and have a rich history
   • Tim Berners-Lee and Robert Caillau at CERN, in 1989-1990 developed HTML as a simplification of SGML
   • CERN launched the web in 1991 (HTML+HTTP)
   • HTML is now at version 4

2. Versions of HTML

   • There are several different version of HTML – HTML 1.0, 2.0, 3.2, 4.0, 4.01 – XHTML 1.0 and 1.1
   • HTML 4.01 and XHTML 1.0 come in different flavours: – Strict: strictly compliant – Transitional: allows some deprecated elements – Frameset: a variant of transitional for documents that use frames
   • For these reasons, every HTML file must begin with a DOCTYPE definition

3. Structure of an HTML Document

   • Every document starts with a DOCTYPE, followed by an HTML section that contains a head and body

4. DOCTYPEs

   • Pros and Cons of different DOCTYPEs – Older DOCTYPEs are supported on older browsers – Newer DOCTYPEs are generally better structured, more standards compliant, and more modular

5. The Document HEAD

   • The HEAD section of the document contains information about the document as opposed to the contents of the document
   • Minimally, it should include a TITLE – <title>My Page Title</title>
   • The HEAD may also include metadata such as character encoding and information about how to format the document

6. The Document BODY

   • The BODY contains the document itself, i.e., what the user sees
   • Any text (also called character data or cdata) within the body must be contained within some other tag

7. Paragraphs

   • The P tag is used to enclose a paragraph of text. <p> Text </p>
   • Paragraphs appear formatted as you would expected