由于缺少结构，即使是形式良好的 HTML 页面也比较难以处理。必须分析标题的级别，才能看出各个部分的划分方式。边栏、页脚、页眉、导航条、主内容区和各篇文章都由通用的 div 元素来表示。HTML 5 添加了一些新元素，专门用来标识这些常见的结构： section：这可以是书中的一章或一节，实际上可以是在 HTML 4 中有自己的标题的任何东西 header：页面上显示的页眉；与 head 元素不一样 footer：页脚；可以显示电子邮件中的签名 nav：指向其他页面的一组链接 article：blog、杂志、文章汇编等中的一篇文章 我们来考虑一个典型的 blog 主页，它的顶部有页眉，底部有页脚，还有几篇文章、一个导航区和一个边栏，见代码1 典型的 blog 页面 html head title Mokka mit Schlag /title /head body div id= page div id= header h1 a href= http://www.elharo.com/blog Mokka mit Schlag /a /h1 /div div id= container div id= center > div > h2 a href= /blog/birding/2007/04/23/spring-comes-and-goes-in-sussex-county/ Spring Comes (and Goes) in Sussex County /a /h2 div > p Yesterday I joined the Brooklyn Bird Club for our annual trip to Western New Jersey, specifically Hyper Humus, a relatively recently discovered hot spot. It started out as a nice winter morning when we arrived at the site at 7:30 A.M., progressed to Spring around 10:00 A.M., and reached early summer by 10:15. /p /div /div div > h2 a href= /blog/birding/2007/04/23/but-does-it-count-for-your-life-list/ But does it count for your life list? /a /h2 div > p Seems you can now go a href= http://www.wired.com/science/discoveries/news/ 2007/04/cone_sf bird watching via the Internet /a . I haven't been able to test it out yet (20 user limit apparently) but this is certainly cool. Personally, I can't imagine it replacing actually being out in the field by any small amount. On the other hand, I've always found it quite sad to meet senior birders who are no longer able to hold binoculars steady or get to the park. I can imagine this might be of some interest to them. At least one elderly birder did a big year on TV, after he could no longer get out so much. This certainly tops that. /p /div /div /div div > div > a href= /blog/page/2/ _fcksavedurl= /blog/page/2/ Previous Entries /a /div div > /div /div div id= right > ul id= sidebar li h2 Info /h2 ul li a href= /blog/comment-policy/ Comment Policy /a /li li a href= /blog/todo-list/ Todo List /a /li /ul /li li h2 Archives /h2 ul li a href='/blog/2007/04/' April 2007 /a /li li a href='/blog/2007/03/' March 2007 /a /li li a href='/blog/2007/02/' February 2007 /a /li li a href='/blog/2007/01/' January 2007 /a /li /ul /li /ul /div div id= footer p Copyright 2007 Elliotte Rusty Harold /p /div /div /body /html 即使有正确的缩进，这些嵌套的 div 仍然让人觉得非常混乱。在 HTML 5 中，可以将这些元素替换为语义性的元素，见代码2 用 HTML5编写的典型blog页面 html head title Mokka mit Schlag /title /head body header h1 a href= http://www.elharo.com/blog Mokka mit Schlag /a /h1 /header section article h2 a href= /blog/birding/2007/04/23/spring-comes-and-goes-in-sussex-county/ Spring Comes (and Goes) in Sussex County /a /h2 p Yesterday I joined the Brooklyn Bird Club for our annual trip to Western New Jersey, specifically Hyper Humus, a relatively recently discovered hot spot. It started out as a nice winter morning when we arrived at the site at 7:30 A.M., progressed to Spring around 10:00 A.M., and reached early summer by 10:15. /p /article article h2 a href= /blog/birding/2007/04/23/but-does-it-count-for-your-life-list/ But does it count for your life list? /a /h2 p Seems you can now go a href= http://www.wired.com/science/discoveries/news/ 2007/04/cone_sf bird watching via the Internet /a . I haven't been able to test it out yet (20 user limit apparently) but this is certainly cool. Personally, I can't imagine it replacing actually being out in the field by any small amount. On the other hand, I've always found it quite sad to meet senior birders who are no longer able to hold binoculars steady or get to the park. I can imagine this might be of some interest to them. At least one elderly birder did a big year on TV, after he could no longer get out so much. This certainly tops that. /p /article nav a href= /blog/page/2/ _fcksavedurl= /blog/page/2/ Previous Entries /a /nav /section nav ul li h2 Info /h2 ul li a href= /blog/comment-policy/ Comment Policy /a /li li a href= /blog/todo-list/ Todo List /a /li /ul /li li h2 Archives /h2 ul li a href='/blog/2007/04/' April 2007 /a /li li a href='/blog/2007/03/' March 2007 /a /li li a href='/blog/2007/02/' February 2007 /a /li li a href='/blog/2007/01/' January 2007 /a /li /ul /li /ul /nav footer p Copyright 2007 Elliotte Rusty Harold /p /footer /body /html 现在不再需要 div 了。不再需要自己设置 class 属性，从标准的元素名就可以推断出各个部分的意义。这对于音频浏览器、手机浏览器和其他非标准浏览器尤其重要。
