33+2 Metadata in HTML
HTML Metadata provides information about a document via text or links in the head element.
Via text, it specifies Title, Application Name, Author Name, Charset Name, Color Scheme, Color Theme, Description Text, Generator Name, Key Words, Referrer Policy, Robot Policy, Security Policy, Redirect Time, Default Stylesheet, Stylesheet Area, Markup Template, Script Data, Script Map, Script Block Area, Script Module Area, or Custom Text.
Via links, it specifies Base URL, Canonical Document, Alternative Stylesheet, Alternative Document, Alternative Feed, Icon, Manifest, Next document, Pingback, Searcher, Stylesheet, Script Block, Script Module, or Custom Link.
How 8 elements creates 33+2 metadata in HTML
The 8 metadata elements in HTML are base, link, meta, noscript, script, style, template, and title.
The base, style, template, and title elements create one metadata each.
The link element, via some keywords of its rel attribute, creates 9 standard metadata and any custom link. Those keywords are icon, manifest, next, pingback, search, and stylesheet. Furthermore, the alternate keyword creates 3 metadata depending on the presence of a stylesheet keyword and whether the type attribute specifies an application Mime Type.
The meta element creates a total of 14 standard metadata and any custom text. One metadata via its charset attribute. Three via the valid keywords in http-equiv attribute: content-security-policy, default-style, and refresh. Ten via the name attribute: application-name, author, description, generator, keywords, referrer, theme-color, color-scheme, viewport (by CSS Standard,) robots (by SEO standard.)
The script element creates 6 metadata via a combination of its type and src attributes.