说明：  HTML5 什么是HTML5：超文本标记语言的第五套标准规范。 对比之前的HTML：之前的版本也就是我们通常使用的HTML是4.01版本。 区别是什么：
(HTML5 What is HTML5: the fifth set of standard specifications for hypertext markup language. Compare the previous HTML: the previous version is that we usually use HTML as the 4.01 version. What is the difference?)