The 36 + 1 Content Metas of HTML

A Content Meta relates an information about the web document to user agents

Each Content Meta must be declared within the Head Container and optionally via a NoScript Container

AppName Meta

The AppName Meta names the application in a document.

The syntax is one void meta element per document with the following attributes:

One name attribute with the application-name value
One content attribute
Zero or one count for each Global Attribute

<meta name="application-name" content="[value]">

Author Meta

An Author Meta names the author of a document.

The syntax is a void meta element with the following attributes:

One name attribute with the author value
One content attribute
Zero or one count for each Global Attribute

<meta name="author" content="[value]">

Base Target Meta

The Base Target Meta specifies the default opening context for all URLs in a web document.

This Meta must precede elements that represent hyperlinks

The syntax is one void base element per document with the following attributes:

One target attribute
Zero or one count for each Global Attribute

<base href="[navigable-name-or-keyword]">

Base URL

The Base URL Meta specifies a prefix for all non-schemed URLs in a web document.

This meta must precede elements with attributes that accept URLs.

The syntax is one void base element per document with the following attributes:

One href attribute
Zero or one count for each Global Attribute

<base href="[URL]">

Canonical Meta

A Canonical Meta names the original document to the current (duplicate) document

The syntax is a one void link element per document with the following attributes:

One rel attribute with the canonical keyword.
One href attribute
Zero or one count for each of the following attributes:
Zero or one count for the title attribute and each other Global Attribute

<link rel="canonical" href="[resource-url]">

Charset Meta

The Charset Meta specifies the character encoding for a web document.

The syntax is one void meta element per document with either of the following attributes:

One charset attribute with the utf-8 value
Both of the following attributes:
- http-equiv attribute with the content-type value
- content attribute with the "text/html; charset=utf-8" value

<meta charset="utf-8">

<!-- or -->

<meta http-equiv="content-type" content="text/html; charset=utf-8">

Description Meta

The Description Meta describes the document.

The syntax is a one void meta element per document with the following attributes:

One name attribute with the description value
One content attribute
Zero or one count for each Global Attribute

<meta name="description" content="[value]">

Feed Meta

A Feed Meta relates an external resource to syndicate the contents of a web document to aggregators

The syntax is a void link element with the following attributes:

One rel attribute with the alternate keyword
One href attribute
One type attribute with a MIME Type value that is either application/rss+xml or application/atom+xml.
Zero or one count for each of the following attributes:
- hreflang
- media
Zero or one count for the title attribute and each other Global Attribute

<link rel="alternate" type="application/rss+xml" href="[resource-url]">
<!-- or -->
<link rel="alternate" type="application/atom+xml" href="[resource-url]">

Generator Meta

A Generator Meta specifies the name of a software that generates a part or the whole of a web document.

The syntax is a void meta element with the following attributes:

One name attribute with the generator value
One content attribute
Zero or one count for each Global Attribute

<meta name="generator" content="[value]">

Icon Meta

An Icon Meta identifies the document with a graphic resource.

The syntax is a void link element with the following attributes:

One rel attribute with the icon keyword
One href attribute
Zero or one count for each of the following attributes:
Zero or one count for the title attribute and each other Global Attribute

<link rel="icon" href="[resource-url]">

Keywords Meta

A Keywords Meta identifies the document with a set of keywords.

The syntax is a void meta element with the following attributes:

One name attribute with the keywords value
One content attribute
Zero or one count for each Global Attribute

<meta name="keywords" content="[value]">

Manifest Meta

A Manifest Meta specifies a JSON resource that provides information about the web application in a web document.

The syntax is a void link element with the following attributes:

One rel attribute with a manifest keyword. And, an optional preload keyword
One href attribute
Zero or one count for each of the following attributes:
Zero or one integrity attribute if the preload keyword is in the rel attribute
Zero or one count for each Global Attribute

<link rel="manifest" href="[url]">

Next Meta

A Next Meta specifies a resource that is next in sequence to the current document.

The syntax is a void link element with the following attributes:

One rel attribute with the next keyword
One href attribute
Zero or one count for each of the following attributes:
Zero or one count for the title attribute and each other Global Attribute

<link rel="next" href="[resource-url]">

Pingback Meta

A Pingback Meta relates a server resource to handle pingbacks to a web document

The syntax is a void link element with the following attributes:

One rel attribute with the pingback keyword
One href attribute
Zero or one count for each of the following attributes:
Zero or one count for the title attribute and each other Global Attribute

<link rel="pingback" href="[url]">

Redirect Meta

The Redirect Meta hints at loading a webpage in a specified time

The syntax is one void meta element per document with the following attributes:

One http-equiv attribute with the refresh value
One content attribute
Zero or one count for each Global Attribute

<meta http-equiv="refresh" content="[value]">

Referrer Meta

A Referrer Meta specifies the default referrer policy of a web document.

The syntax is a void meta element with the following attributes:

One name attribute with the referrer value
One content attribute
Zero or one count for each Global Attribute

<meta name="referrer" content="[value]">

Reform Meta

A Reform Meta specifies a version of the current document in another format.

The syntax is a void link element with the following attributes:

One rel attribute with the alternate keyword
One href attribute
One type attribute without the application/rss+xml value or the application/atom+xml value.
Zero or one count for each of the following attributes:
- hreflang
- media
Zero or one count for the title attribute and each other Global Attribute

<link rel="alternate" href="[URL]" type="[valid-MIME-TYPE]">

Robots

The Robots Meta hints search engines on how to use a webpage

The syntax is a one void meta element with the following attributes:

One count for name attribute and content attribute
Zero or one count for each Global Attribute

<meta name="[og:name]" content="[value]">

Scheme Meta

The Scheme Meta relates the color scheme to use as default for a web document.

The syntax is one void meta element per document with the following attributes:

One name attribute with the color-scheme value
One content attribute
Zero or one count for each Global Attribute

<meta name="color-scheme" content="[value]">

Script Meta

A Script Meta specifies javascript instructions on a web document for dynamic contents.

Script Link

A Script Link relates an external resource of javascript instructions

The syntax is a script element with the following attributes and content:

One type attribute with an empty string or a [Javascript MIME Type essence match]
One src attribute
Zero or one count for each of the following attributes:
Zero or one count for each Global Attribute
An optional text content matching script content restrictions and conforming to a script documentation

<script src="[valid-URL]"></script>

Script Area

A Script Area relates an embed of javascript instructions

The syntax is a script element with the following attributes and content:

One type attribute with an empty string or a [Javascript MIME Type essence match]
Zero or one count for each of the following attributes:
Zero or one count for each Global Attribute
A text content matching script content restrictions and conforming to the value of the type attribute

<script>

</script>

Module Link

A Module Link enables reuse of an external resource of javascript instructions

The syntax is a script element with the following conditions:

One type attribute with a module value
One src attribute
Zero or one count for each of the following attributes:

<script type="module" src="[URL]">

</script>

Module Area

A Module Area enables reuse of an embedded resource of javascript instructions

The syntax is a script element with the following conditions:

One type attribute with a module value
Zero or one count for each of the following attributes:
A Text that conforms to the requirement of the Javascript's Module production

<script type="module">

</script>

Import Map

An Import Map specifies a JSON resource to resolve Javascript Modules

The syntax is one script element per document with the following attributes and content:

One type attribute with an importmap value
Zero or one count for each of the following attributes:
- blocking
- fetchpriority
A text content that conforms to the import map authoring requirements

<script type="importmap"></script>

Data Block

A Data Block specifies data for use in Javascript Instructions.

The syntax is a script element with the following attributes and content:

One type attribute with a value other than a module, an importmap, an empty string, or a Javascript MIME type essence
A text content that conforms to the import map authoring requirements

<script type="[other-types]"></script>

Search Meta

A Search Meta relates an external resource to discover the contents of the current document.

The syntax is a void link element with the following attributes:

One rel attribute with the search keyword
One href attribute
Zero or one count for each of the following attributes:
Zero or one count for the title attribute and each other Global Attribute

<link rel="search" href="[resource-url]">

Search Meta

A Search Meta relates an external resource to discover the contents of the current document.

The syntax is a void link element with the following attributes:

One rel attribute with the search keyword
One href attribute
Zero or one count for each of the following attributes:
Zero or one count for the title attribute and each other Global Attribute

<link rel="search" href="[resource-url]">

Security Meta

The Security Meta specifies a policy to secure the content of a web document.

The syntax is one void meta element per document with the following attributes:

One http-equiv attribute with the content-security-policy value
One content attribute
Zero or one count for each Global Attribute

<meta http-equiv="content-security-policy" content="[value]">

Stylesheet Meta

A Stylesheet Meta relates a set of CSS Rules for a document.

Each set may be embedded on or externalized to the page. A collection of stylesheets with the same title make up a theme. One theme can be the default.

Style Link

A Style Link relates an external resource of CSS Rules

The syntax is a void link element with the following attributes:

One rel attribute with the stylesheet keyword.
One href attribute
Zero or one count for each of the following attributes:
Zero or one count for the title attribute and each other Global Attribute

<link rel="stylesheet" href="[URL]">

Style Area

A Style Area relates an embedded resource of CSS Rules

The syntax is a style element with the following attributes and content:

Zero or one count for each of the following attributes:
- blocking
- media
Zero or one count for the title attribute and each other Global Attribute
A text content that gives a conformant style sheet

<style>
  /* text that is style conformant */
</style>

Style Alternative

A Style Alternative relates an external resource of alternative CSS Rules

The syntax is a void link element with the following attributes:

One rel attribute with the stylesheet and alternate keywords.
One href attribute
Zero or one count for each of the following attributes:
Zero or one count for the title attribute and each other Global Attribute

<link rel="alternate stylesheet" href="[URL]">

Style Default

The Style Default Meta hints the initial stylesheet set of a web page.

The syntax is a void meta element per document with the following attributes:

One http-equiv attribute with the default-style value
One content attribute
Zero or one count for each Global Attribute

<meta http-equiv="default-style" content="[title-namr]">

Template Meta

A Template Meta specifies a fragment of an HTML document with optional placeholders

The syntax is a template element with the following attributes and contents:

Zero or one count for each of the following attributes:
Zero or one count for each Global Attribute
Zero or more counts for each Flow Content Element.

<template>

</template>

Theme Meta

A Theme Meta relates the color to customize the interface of the user agent.

The syntax is a void meta element with the following attributes:

One name attribute with the theme-color value
One content attribute
Zero or one media attribute
Zero or one count for each Global Attribute

<meta name="theme-color" content="[value]">

Title Meta

The Title Meta elaborates the document name.

A document must have a Title Meta, except for each of the following cases:

The document is an iframe element with a srcdoc attribute
The title information is available from a higher-level protocol

The syntax is one title element per document with the following attributes and content:

Zero or one count for each Global Attribute
A non-empty text content

<title> [non-empty text] </title>

Translation Meta

A Translation Meta specifies a version of the current document in another language.

The syntax is a void link element with the following attributes:

One rel attribute with the alternate keyword
One href attribute
One hreflang attribute with a language different from that of the document
Zero or one count for each of the following attributes:
- media
- type
Zero or one count for the title attribute and each other Global Attribute

<link rel="alternate" hreflang="[not-document-language]" href="[resource-url]">

Viewport Meta

The Viewport Meta hints the initial size of the viewing area of a web page.

The syntax is a void meta element per document with the following attributes:

One name attribute with the viewport value
One content attribute
Zero or one count for each Global Attribute

<meta name="viewport" content="[value]">

Custom Meta

A Custom Meta relates a non-standard metadata

The syntax is a void link element if value will be a URL otherwise a void meta element. It takes Zero or one count for each Attribute

<link rel="[custom-keyword]" href="[URL]">

<!-- or -->

<meta name="[custom-name]" content="[custom-value]">

Appendix

The following utilities applies to Content Metas

Head Container

The Head Container specifies a collection of Content Metas to User Agents for processing

The syntax is an head element with the following attributes and contents:

Zero or one count for each Global Attribute
Zero or more counts for most Content Metas

<head>
  <!-- Content Metas -->
</head>

Noscript Container

A Noscript Container in a Meta Container relates Content Metas to User Agents that doesn't support scripting functionality on a web document.

The syntax is a noscript element with the following attributes and child elements:

Zero or one count for each Global Attribute
Zero or more counts for each Content Metas except the following: Title Meta, Url Meta, Target Meta, Template Meta, and loaded (not preloaded) Script Meta

<noscript>

</noscript>

Slot Wrapper

A Template Placeholder specifies a replaceable part within a reusable markup

The syntax is a slot element with the following attributes and contents:

Zero or one slot attribute
Zero or one count for each Global Attribute
Zero or one count for each element allowed in the parent element

<slot></slot>