Html5

Jeremy Keith

Copyright © 2010 by Jeremy Keith All rights reserved Publisher: Jeffrey Zeldman Designer: Jason Santa Maria Editor: Mandy Brown Technical Editor: Ethan Marcotte Copyeditor: Krista Stevens ISBN 978-0-9844425-0-8 A Book Apart New York, New York http://books.alistapart.com 1234567890

chapter 1

A Brief History of Markup
chapter 2

The Design of HTML5
chapter 3

RichMedia
chapter 4

Web Forms 2.0
chapter 5

Semantics
chapter 6

Using HTML5 Today Index

When Mandy Brown, Jason Santa Maria and I formed A Book Apart, one topic burned uppermost in our minds, and there was only one author for the job. Nothing else, not even “real fonts” or CSS3, has stirred the standards-based design community like the imminent arrival of HTML5. Born out ofdissatisfaction with the pacing and politics of the W3C, and conceived for a web of applications (not just documents), this new edition of the web’s lingua franca has in equal measure excited, angered, and confused the web design community. Just as he did with the DOM and JavaScript, Jeremy Keith has a unique ability to illuminate HTML5 and cut straight to what matters to accessible, standards-baseddesigner-developers. And he does it in this book, using only as many words and pictures as are needed. There are other books about HTML5, and there will be many more. There will be 500 page technical books for application developers, whose needs drove much of HTML5’s development. There will be even longer secret books for browser makers, addressing technical challenges that you and I are blessed never toneed to think about. But this is a book for you—you who create web content, who mark up web pages for sense and semantics, and who design accessible interfaces and experiences. Call it your user guide to HTML5. Its goal—one it will share with every title in the forthcoming A Book Apart catalog—is to shed clear light on a tricky subject, and do it fast, so you can get back to work. —Jeffrey Zeldmanhtml is the unifying language of the World Wide Web. Using just the simple tags it contains, the human race has created an astoundingly diverse network of hyperlinked documents, from Amazon, eBay, and Wikipedia, to personal blogs and websites dedicated to cats that look like Hitler. HTML5 is the latest iteration of this lingua franca. While it is the most ambitious change to our common tongue,this isn’t the first time that HTML has been updated. The language has been evolving from the start. As with the web itself, the HyperText Markup Language was the brainchild of Sir Tim Berners-Lee. In 1991 he wrote a document called “HTML Tags” in which he proposed fewer than two dozen elements that could be used for writing web pages. Sir Tim didn’t come up with the idea of using tags consistingof words between angle brackets; those kinds of tags already existed in the SGML (Standard Generalized Markup Language)

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format. Rather than inventing a new standard, Sir Tim saw the benefit of building on top of what already existed—a trend that can still be seen in the development of HTML5.

There was never any such thing as HTML 1. The firstofficial specification was HTML 2.0, published by the IETF, the Internet Engineering Task Force. Many of the features in this specification were driven by existing implementations. For example, the market-leading Mosaic web browser of 1994 already provided a way for authors to embed images in their documents using an tag. The img element later appeared in the HTML 2.0 specification. The role ofthe IETF was superceded by the W3C, the World Wide Web Consortium, where subsequent iterations of the HTML standard have been published at http://www.w3.org. The latter half of the nineties saw a flurry of revisions to the specification until HTML 4.01 was published in 1999. At that time, HTML faced its first major turning point.

After HTML 4.01, the next revision to the language was called...