说明：  This book will show you how to create your own documents so you can share them on the Web. You’ll become intimately familiar with the rules and constructs of HyperText Markup Language (HTML), the computer language on which the Web is built. It’s a simple language, and the basic rules are easy to pick up and put to use. HTML is a tool, and once you know how to use it, you’re limited only by your imagination. Like any other language, HTML has changed and evolved over time. New features are added, existing features are redefined, and outdated features are removed. The latest iteration of HTML is HTML5— ostensibly the fifth version of the language—and it’s quite an evolutionary leap indeed. HTML5 incorporates a wide range of new features and introduces new types of functionality far beyond the humble text document.include Source code