section HTML Spec: “The section element represents a generic section of a document or application. A section, in this context, is a thematic grouping of content, typically with a heading.”
与 div 的无语义相对，简单地说 section 就是带有语义的 div 了，但是千万不要觉得真得这么简单。section 表示一段专题性的内容，一般会带有标题。看到这里，我们也许会想到，那么一篇博客文章，或者一条单独的评论岂不是正好可以用 section 吗？接着看：
“Authors are encouraged to use the article element instead of the section element when it would make sense to syndicate the contents of the elemen.”
当元素内容聚合起来更加言之有物时，应该使用 article 来替换 section 。
那么，section 应该什么时候用呢？再接着看：
“Examples of sections would be chapters, the various tabbed pages in a tabbed dialog box, or the numbered sections of a thesis. A Web site’s home page could be split into sections for an introduction, news items, and contact information.”
“The section element is not a generic container element. When an element is needed for styling purposes or as a convenience for scripting, authors are encouraged to use the div element instead. A general rule is that the section element is appropriate only if the element’s contents would be listed explicitly in the document’s outline.”
section 不仅仅是一个普通的容器标签。当一个标签只是为了样式化或者方便脚本使用时，应该使用 div 。一般来说，当元素内容明确地出现在文档大纲中时，section 就是适用的。
article HTML Spec: “The article element represents a self-contained composition in a document, page, application, or site and that is, in principle, independently distributable or reusable, e.g. in syndication.”
HTML Spec 中接着又列举了一些 article 适用的场景。 “This could be a forum post, a magazine or newspaper article, a blog entry, a user-submitted comment, an interactive widget or gadget, or any other independent item of content.”
