13.2 Provide metadata to add semantic information to pages and sites

Some structural tags provide information about the document itself. This is called metadata. Good quality metadata provides useful and accurate keywords and descriptions of content and media types. The descriptions and summaries of page contents displayed by search engines are often taken from metadata on a pages.

Metadata can also provide important contextual information to help you understand and navigate through content. Examples of metadata include descriptions of the contents and structural organisation of complex tables or long lists.

The tags that provide useful information about a document include:

• The <!doctype> tag lets the user know that the structure of the document is sound. It also lets the browser know where to look for semantics if it needs to
• The <title> tag contains the title of the page
• The <address> tag can provide information about the creator of the page
• The <meta> tag can specify metadata for a document including keywords
• The <link> tag describe document navigation mechanisms and organization.