The

element represents a generic section of a document or application. A section, in this context, is a thematic grouping of content. Each section should be identified, typically by including a heading (h1-h6 element) as a child of the

element.

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

element is not a generic container element. When an element is needed only for styling purposes or as a convenience for scripting, authors are encouraged to use the element instead. A general rule is that the

element is appropriate only if the element’s contents would be listed explicitly in the document’s outline.

(https://www.w3.org/tr/html/sections.html节元素)

The element has no special meaning at all. It represents its children. It can be used with the class, lang, and title attributes to mark up semantics common to a group of consecutive elements.

Note: Authors are strongly encouraged to view the element as an element of last resort, for when no other element is suitable. Use of more appropriate elements instead of the element leads to better accessibility for readers and easier maintainability for authors.

(https://www.w3.org/tr/html/grouping content.html the div元素)