1. 4 The elements of HTML
    1. 4.1 The document element
      1. 4.1.1 The html element
    2. 4.2 Document metadata
      1. 4.2.1 The head element
      2. 4.2.2 The title element
      3. 4.2.3 The base element
      4. 4.2.4 The link element
        1. 4.2.4.1 Providing users with a means to follow hyperlinks created using the link element
      5. 4.2.5 The meta element
        1. 4.2.5.1 Standard metadata names
        2. 4.2.5.2 Other metadata names
        3. 4.2.5.3 Pragma directives
        4. 4.2.5.4 Specifying the document's character encoding
      6. 4.2.6 The style element

4 The elements of HTML

4.1 The document element

4.1.1 The html element

Element/html

Support in all current engines.

Firefox1+Safari1+Chrome1+
Opera12.1+Edge79+
Edge (Legacy)12+Internet ExplorerYes
Firefox Android?Safari iOS?Chrome Android?WebView Android?Samsung Internet?Opera Android12.1+
Categories:
None.
Contexts in which this element can be used:
As document's document element.
Wherever a subdocument fragment is allowed in a compound document.
Content model:
A head element followed by a body element.
Tag omission in text/html:
An html element's start tag can be omitted if the first thing inside the html element is not a comment.
An html element's end tag can be omitted if the html element is not immediately followed by a comment.
Content attributes:
Global attributes
Accessibility considerations:
For authors.
For implementers.
DOM interface:
Uses HTMLHtmlElement.

The html element represents the root of an HTML document.

Authors are encouraged to specify a lang attribute on the root html element, giving the document's language. This aids speech synthesis tools to determine what pronunciations to use, translation tools to determine what rules to use, and so forth.

The html element in the following example declares that the document's language is English.

<!DOCTYPE html>
<html lang="en">
<head>
<title>Swapping Songs</title>
</head>
<body>
<h1>Swapping Songs</h1>
<p>Tonight I swapped some of the songs I wrote with some friends, who
gave me some of the songs they wrote. I love sharing my music.</p>
</body>
</html>

4.2 Document metadata

4.2.1 The head element

Element/head

Support in all current engines.

Firefox1+Safari1+Chrome1+
Opera?Edge79+
Edge (Legacy)12+Internet ExplorerYes
Firefox Android?Safari iOS?Chrome Android?WebView Android?Samsung Internet?Opera Android?
Categories:
None.
Contexts in which this element can be used:
As the first element in an html element.
Content model:
If the document is an iframe srcdoc document or if title information is available from a higher-level protocol: Zero or more elements of metadata content, of which no more than one is a title element and no more than one is a base element.
Otherwise: One or more elements of metadata content, of which exactly one is a title element and no more than one is a base element.
Tag omission in text/html:
A head element's start tag can be omitted if the element is empty, or if the first thing inside the head element is an element.
A head element's end tag can be omitted if the head element is not immediately followed by ASCII whitespace or a comment.
Content attributes:
Global attributes
Accessibility considerations:
For authors.
For implementers.
DOM interface:
Uses HTMLHeadElement.

The head element represents a collection of metadata for the Document.

The collection of metadata in a head element can be large or small. Here is an example of a very short one:

<!doctype html>
<html lang=en>
 <head>
  <title>A document with a short head</title>
 </head>
 <body>
 ...

Here is an example of a longer one:

<!DOCTYPE HTML>
<HTML LANG="EN">
 <HEAD>
  <META CHARSET="UTF-8">
  <BASE HREF="https://www.example.com/">
  <TITLE>An application with a long head</TITLE>
  <LINK REL="STYLESHEET" HREF="default.css">
  <LINK REL="STYLESHEET ALTERNATE" HREF="big.css" TITLE="Big Text">
  <SCRIPT SRC="support.js"></SCRIPT>
  <META NAME="APPLICATION-NAME" CONTENT="Long headed application">
 </HEAD>
 <BODY>
 ...

The title element is a required child in most situations, but when a higher-level protocol provides title information, e.g., in the subject line of an email when HTML is used as an email authoring format, the title element can be omitted.

4.2.2 The title element

Element/title

Support in all current engines.

Firefox1+Safari1+Chrome1+
Opera?Edge79+
Edge (Legacy)12+Internet Explorer1+
Firefox Android?Safari iOS?Chrome Android?WebView Android?Samsung Internet?Opera Android?
Categories:
Metadata content.
Contexts in which this element can be used:
In a head element containing no other title elements.
Content model:
Text that is not inter-element whitespace.
Tag omission in text/html:
Neither tag is omissible.
Content attributes:
Global attributes
Accessibility considerations:
For authors.
For implementers.
DOM interface:
Uses HTMLTitleElement.

The title element represents the document's title or name. Authors should use titles that identify their documents even when they are used out of context, for example in a user's history or bookmarks, or in search results. The document's title is often different from its first heading, since the first heading does not have to stand alone when taken out of context.

There must be no more than one title element per document.

If it's reasonable for the Document to have no title, then the title element is probably not required. See the head element's content model for a description of when the element is required.

title.text [ = value ]

Returns the child text content of the element.

Can be set, to replace the element's children with the given value.

Here are some examples of appropriate titles, contrasted with the top-level headings that might be used on those same pages.

  <title>Introduction to The Mating Rituals of Bees</title>
    ...
  <h1>Introduction</h1>
  <p>This companion guide to the highly successful
  <cite>Introduction to Medieval Bee-Keeping</cite> book is...

The next page might be a part of the same site. Note how the title describes the subject matter unambiguously, while the first heading assumes the reader knows what the context is and therefore won't wonder if the dances are Salsa or Waltz:

  <title>Dances used during bee mating rituals</title>
    ...
  <h1>The Dances</h1>

The string to use as the document's title is given by the document.title IDL attribute.

4.2.3 The base element

Element/base

Support in all current engines.

Firefox1+Safari3+Chrome1+
Opera?Edge79+
Edge (Legacy)12+Internet ExplorerYes
Firefox Android?Safari iOS?Chrome Android?WebView Android?Samsung Internet?Opera Android?
Categories:
Metadata content.
Contexts in which this element can be used:
In a head element containing no other base elements.
Content model:
Nothing.
Tag omission in text/html:
No end tag.
Content attributes:
Global attributes
hrefDocument base URL
target — Default navigable for hyperlink navigation and form submission
Accessibility considerations:
For authors.
For implementers.
DOM interface:
Uses HTMLBaseElement.

The base element allows authors to specify the document base URL for the purposes of parsing URLs, and the name of the default navigable for the purposes of following hyperlinks. The element does not represent any content beyond this information.

There must be no more than one base element per document.

A base element must have either an href attribute, a target attribute, or both.

The href content attribute, if specified, must contain a valid URL potentially surrounded by spaces.

A base element, if it has an href attribute, must come before any other elements in the tree that have attributes defined as taking URLs, except the html element (its manifest attribute isn't affected by base elements).

The target attribute, if specified, must contain a valid navigable target name or keyword, which specifies which navigable is to be used as the default when hyperlinks and forms in the Document cause navigation.

A base element, if it has a target attribute, must come before any elements in the tree that represent hyperlinks.

In this example, a base element is used to set the document base URL:

<!DOCTYPE html>
<html lang="en">
    <head>
        <title>This is an example for the &lt;base&gt; element</title>
        <base href="https://www.example.com/news/index.html">
    </head>
    <body>
        <p>Visit the <a href="archives.html">archives</a>.</p>
    </body>
</html>

The link in the above example would be a link to "https://www.example.com/news/archives.html".

Element/link

Support in all current engines.

Firefox1+Safari4+Chrome1+
Opera12.1+Edge79+
Edge (Legacy)12+Internet ExplorerYes
Firefox Android?Safari iOS?Chrome Android?WebView Android?Samsung Internet?Opera Android12.1+
Categories:
Metadata content.
If the element is allowed in the body: flow content.
If the element is allowed in the body: phrasing content.
Contexts in which this element can be used:
Where metadata content is expected.
In a noscript element that is a child of a head element.
If the element is allowed in the body: where phrasing content is expected.
Content model:
Nothing.
Tag omission in text/html:
No end tag.
Content attributes:
Global attributes
href — Address of the hyperlink
crossorigin — How the element handles crossorigin requests
rel — Relationship between the document containing the hyperlink and the destination resource
media — Applicable media
integrity — Integrity metadata used in Subresource Integrity checks [SRI]
hreflang — Language of the linked resource
type — Hint for the type of the referenced resource
referrerpolicyReferrer policy for fetches initiated by the element
sizes — Sizes of the icons (for rel="icon")
imagesrcset — Images to use in different situations, e.g., high-resolution displays, small monitors, etc. (for rel="preload")
imagesizes — Image sizes for different page layouts (for rel="preload")
asPotential destination for a preload request (for rel="preload" and rel="modulepreload")
blocking — Whether the element is potentially render-blocking
color — Color to use when customizing a site's icon (for rel="mask-icon")
disabled — Whether the link is disabled
fetchpriority — Sets the priority for fetches initiated by the element
Also, the title attribute has special semantics on this element: Title of the link; CSS style sheet set name
Accessibility considerations:
For authors.
For implementers.
DOM interface:
Uses HTMLLinkElement.

The link element allows authors to link their document to other resources.

The address of the link(s) is given by the href attribute. If the href attribute is present, then its value must be a valid non-empty URL potentially surrounded by spaces. One or both of the href or imagesrcset attributes must be present.

The types of link indicated (the relationships) are given by the value of the rel attribute, which, if present, must have a value that is a unordered set of unique space-separated tokens. The allowed keywords and their meanings are defined in a later section.

A link element must have either a rel attribute or an itemprop attribute, but not both.

If a link element has an itemprop attribute, or has a rel attribute that contains only keywords that are body-ok, then the element is said to be allowed in the body. This means that the element can be used where phrasing content is expected.

If the rel attribute is used, the element can only sometimes be used in the body of the page. When used with the itemprop attribute, the element can be used both in the head element and in the body of the page, subject to the constraints of the microdata model.


Two categories of links can be created using the link element: links to external resources and hyperlinks. The link types section defines whether a particular link type is an external resource or a hyperlink. One link element can create multiple links (of which some might be external resource links and some might be hyperlinks); exactly which and how many links are created depends on the keywords given in the rel attribute. User agents must process the links on a per-link basis, not a per-element basis.

Each link created for a link element is handled separately. For instance, if there are two link elements with rel="stylesheet", they each count as a separate external resource, and each is affected by its own attributes independently. Similarly, if a single link element has a rel attribute with the value next stylesheet, it creates both a hyperlink (for the next keyword) and an external resource link (for the stylesheet keyword), and they are affected by other attributes (such as media or title) differently.

For example, the following link element creates two hyperlinks (to the same page):

<link rel="author license" href="/about">

The two links created by this element are one whose semantic is that the target page has information about the current page's author, and one whose semantic is that the target page has information regarding the license under which the current page is provided.

Hyperlinks created with the link element and its rel attribute apply to the whole document. This contrasts with the rel attribute of a and area elements, which indicates the type of a link whose context is given by the link's location within the document.

Unlike those created by a and area elements, hyperlinks created by link elements are not displayed as part of the document by default, in user agents that support the suggested default rendering. And even if they are force-displayed using CSS, they have no activation behavior. Instead, they primarily provide semantic information which might be used by the page or by other software that consumes the page's contents. Additionally, the user agent can provide its own UI for following such hyperlinks.

The exact behavior for links to external resources depends on the exact relationship, as defined for the relevant link type.


The crossorigin attribute is a CORS settings attribute. It is intended for use with external resource links.

The media attribute says which media the resource applies to. The value must be a valid media query list.

Subresource_Integrity

Support in all current engines.

Firefox43+Safari11.1+Chrome45+
Opera?Edge79+
Edge (Legacy)17+Internet ExplorerNo
Firefox Android?Safari iOS?Chrome Android?WebView Android?Samsung Internet?Opera Android?

The integrity attribute represents the integrity metadata for requests which this element is responsible for. The value is text. The attribute must only be specified on link elements that have a rel attribute that contains the stylesheet, preload, or modulepreload keyword. [SRI]

The hreflang attribute on the link element has the same semantics as the hreflang attribute on the a element.

The type attribute gives the MIME type of the linked resource. It is purely advisory. The value must be a valid MIME type string.

For external resource links, the type attribute is used as a hint to user agents so that they can avoid fetching resources they do not support.

The referrerpolicy attribute is a referrer policy attribute. It is intended for use with external resource links, where it helps set the referrer policy used when fetching and processing the linked resource. [REFERRERPOLICY].

The title attribute gives the title of the link. With one exception, it is purely advisory. The value is text. The exception is for style sheet links that are in a document tree, for which the title attribute defines CSS style sheet sets.

The title attribute on link elements differs from the global title attribute of most other elements in that a link without a title does not inherit the title of the parent element: it merely has no title.


The imagesrcset attribute may be present, and is a srcset attribute.

The imagesrcset and href attributes (if width descriptors are not used) together contribute the image sources to the source set.

If the imagesrcset attribute is present and has any image candidate strings using a width descriptor, the imagesizes attribute must also be present, and is a sizes attribute. The imagesizes attribute contributes the source size to the source set.

The imagesrcset and imagesizes attributes must only be specified on link elements that have both a rel attribute that specifies the preload keyword, as well as an as attribute in the "image" state.

These attributes allow preloading the appropriate resource that is later used by an img element that has the corresponding values for its srcset and sizes attributes:

<link rel="preload" as="image"
      imagesrcset="wolf_400px.jpg 400w, wolf_800px.jpg 800w, wolf_1600px.jpg 1600w"
      imagesizes="50vw">

<!-- ... later, or perhaps inserted dynamically ... -->
<img src="wolf.jpg" alt="A rad wolf"
     srcset="wolf_400px.jpg 400w, wolf_800px.jpg 800w, wolf_1600px.jpg 1600w"
     sizes="50vw">

Note how we omit the href attribute, as it would only be relevant for browsers that do not support imagesrcset, and in those cases it would likely cause the incorrect image to be preloaded.

The imagesrcset attribute can be combined with the media attribute to preload the appropriate resource selected from a picture element's sources, for art direction:

<link rel="preload" as="image"
      imagesrcset="dog-cropped-1x.jpg, dog-cropped-2x.jpg 2x"
      media="(max-width: 800px)">
<link rel="preload" as="image"
      imagesrcset="dog-wide-1x.jpg, dog-wide-2x.jpg 2x"
      media="(min-width: 801px)">

<!-- ... later, or perhaps inserted dynamically ... -->
<picture>
  <source srcset="dog-cropped-1x.jpg, dog-cropped-2x.jpg 2x"
          media="(max-width: 800px)">
  <img src="dog-wide-1x.jpg" srcset="dog-wide-2x.jpg 2x"
       alt="An awesome dog">
</picture>

The sizes attribute gives the sizes of icons for visual media. Its value, if present, is merely advisory. If specified, the attribute must have a value that is an unordered set of unique space-separated tokens which are ASCII case-insensitive. Each value must be either an ASCII case-insensitive match for the string "any", or a value that consists of two valid non-negative integers that do not have a leading U+0030 DIGIT ZERO (0) character and that are separated by a single U+0078 LATIN SMALL LETTER X or U+0058 LATIN CAPITAL LETTER X character. The attribute must only be specified on link elements that have a rel attribute that specifies the icon keyword or the apple-touch-icon keyword.

The apple-touch-icon keyword is a registered extension to the predefined set of link types, but user agents are not required to support it in any way.


The as attribute specifies the potential destination for a preload request for the resource given by the href attribute. It is an enumerated attribute. Each potential destination is a keyword for this attribute, mapping to a state of the same name. The attribute must be specified on link elements that have a rel attribute that contains the preload keyword. It may be specified on link elements that have a rel attribute that contains the modulepreload keyword; in such cases it must have a value which is a script-like destination. For other link elements, it must not be specified.

The attribute does not have a missing value default or invalid value default, meaning that invalid or missing values for the attribute map to no state. This is accounted for in the processing model. For preload links, both conditions are an error; for modulepreload links, a missing value will be treated as "script".


The blocking attribute is a blocking attribute. It is used by link type stylesheet, and it must only be specified on link elements that have a rel attribute containing that keyword.


The color attribute is used with the mask-icon link type. The attribute must only be specified on link elements that have a rel attribute that contains the mask-icon keyword. The value must be a string that matches the CSS <color> production, defining a suggested color that user agents can use to customize the display of the icon that the user sees when they pin your site.

This specification does not have any user agent requirements for the color attribute.

The mask-icon keyword is a registered extension to the predefined set of link types, but user agents are not required to support it in any way.


link elements have an associated explicitly enabled boolean. It is initially false.

The disabled attribute is a boolean attribute that is used with the stylesheet link type. The attribute must only be specified on link elements that have a rel attribute that contains the stylesheet keyword.

Whenever the disabled attribute is removed, set the link element's explicitly enabled attribute to true.

Removing the disabled attribute dynamically, e.g., using document.querySelector("link").removeAttribute("disabled"), will fetch and apply the style sheet:

<link disabled rel="alternate stylesheet" href="css/pooh">

HTMLLinkElement/fetchPriority

FirefoxNoSafari🔰 preview+Chrome102+
Opera?Edge102+
Edge (Legacy)?Internet ExplorerNo
Firefox Android?Safari iOS?Chrome Android?WebView Android?Samsung Internet?Opera Android?

The fetchpriority attribute is a fetch priority attribute that is intended for use with external resource links, where it is used to set the priority used when fetching and processing the linked resource.

Interactive user agents may provide users with a means to follow the hyperlinks created using the link element, somewhere within their user interface. Such invocations of the follow the hyperlink algorithm must set the userInvolvement argument to "browser UI". The exact interface is not defined by this specification, but it could include the following information (obtained from the element's attributes, again as defined below), in some form or another (possibly simplified), for each hyperlink created with each link element in the document:

User agents could also include other information, such as the type of the resource (as given by the type attribute).

4.2.5 The meta element

Element/meta

Support in all current engines.

Firefox1+Safari1+Chrome1+
Opera12.1+Edge79+
Edge (Legacy)12+Internet ExplorerYes
Firefox Android?Safari iOS?Chrome Android?WebView Android?Samsung Internet?Opera Android12.1+
Categories:
Metadata content.
If the itemprop attribute is present: flow content.
If the itemprop attribute is present: phrasing content.
Contexts in which this element can be used:
If the charset attribute is present, or if the element's http-equiv attribute is in the Encoding declaration state: in a head element.
If the http-equiv attribute is present but not in the Encoding declaration state: in a head element.
If the http-equiv attribute is present but not in the Encoding declaration state: in a noscript element that is a child of a head element.
If the name attribute is present: where metadata content is expected.
If the itemprop attribute is present: where metadata content is expected.
If the itemprop attribute is present: where phrasing content is expected.
Content model:
Nothing.
Tag omission in text/html:
No end tag.
Content attributes:
Global attributes
name — Metadata name
http-equiv — Pragma directive
content — Value of the element
charsetCharacter encoding declaration
media — Applicable media
Accessibility considerations:
For authors.
For implementers.
DOM interface:
Uses HTMLMetaElement.

The meta element represents various kinds of metadata that cannot be expressed using the title, base, link, style, and script elements.

The meta element can represent document-level metadata with the name attribute, pragma directives with the http-equiv attribute, and the file's character encoding declaration when an HTML document is serialized to string form (e.g. for transmission over the network or for disk storage) with the charset attribute.

Exactly one of the name, http-equiv, charset, and itemprop attributes must be specified.

If either name, http-equiv, or itemprop is specified, then the content attribute must also be specified. Otherwise, it must be omitted.

The charset attribute specifies the character encoding used by the document. This is a character encoding declaration. If the attribute is present, its value must be an ASCII case-insensitive match for the string "utf-8".

The charset attribute on the meta element has no effect in XML documents, but is allowed in XML documents in order to facilitate migration to and from XML.

There must not be more than one meta element with a charset attribute per document.

The content attribute gives the value of the document metadata or pragma directive when the element is used for those purposes. The allowed values depend on the exact context, as described in subsequent sections of this specification.

If a meta element has a name attribute, it sets document metadata. Document metadata is expressed in terms of name-value pairs, the name attribute on the meta element giving the name, and the content attribute on the same element giving the value. The name specifies what aspect of metadata is being set; valid names and the meaning of their values are described in the following sections. If a meta element has no content attribute, then the value part of the metadata name-value pair is the empty string.

The media attribute says which media the metadata applies to. The value must be a valid media query list. Unless the name is theme-color, the media attribute has no effect on the processing model and must not be used by authors.

4.2.5.1 Standard metadata names

Element/meta/name

Support in all current engines.

Firefox1+Safari4+Chrome1+
Opera12.1+Edge79+
Edge (Legacy)12+Internet Explorer6+
Firefox Android?Safari iOS?Chrome Android?WebView Android?Samsung Internet?Opera Android12.1+

This specification defines a few names for the name attribute of the meta element.

Names are case-insensitive, and must be compared in an ASCII case-insensitive manner.

application-name

The value must be a short free-form string giving the name of the web application that the page represents. If the page is not a web application, the application-name metadata name must not be used. Translations of the web application's name may be given, using the lang attribute to specify the language of each name.

There must not be more than one meta element with a given language and where the name attribute value is an ASCII case-insensitive match for application-name per document.

author

The value must be a free-form string giving the name of one of the page's authors.

description

The value must be a free-form string that describes the page. The value must be appropriate for use in a directory of pages, e.g. in a search engine. There must not be more than one meta element where the name attribute value is an ASCII case-insensitive match for description per document.

generator

The value must be a free-form string that identifies one of the software packages used to generate the document. This value must not be used on pages whose markup is not generated by software, e.g. pages whose markup was written by a user in a text editor.

Here is what a tool called "Frontweaver" could include in its output, in the page's head element, to identify itself as the tool used to generate the page:

<meta name=generator content="Frontweaver 8.2">
keywords

The value must be a set of comma-separated tokens, each of which is a keyword relevant to the page.

This page about typefaces on British motorways uses a meta element to specify some keywords that users might use to look for the page:

<!DOCTYPE HTML>
<html lang="en-GB">
 <head>
  <title>Typefaces on UK motorways</title>
  <meta name="keywords" content="british,type face,font,fonts,highway,highways">
 </head>
 <body>
  ...

Many search engines do not consider such keywords, because this feature has historically been used unreliably and even misleadingly as a way to spam search engine results in a way that is not helpful for users.

referrer

The value must be a referrer policy, which defines the default referrer policy for the Document. [REFERRERPOLICY]

theme-color

Element/meta/name/theme-color

FirefoxNoSafari15+Chrome🔰 73+
OperaNoEdge🔰 79+
Edge (Legacy)?Internet ExplorerNo
Firefox Android?Safari iOS?Chrome Android80+WebView AndroidNoSamsung Internet6.2+Opera AndroidNo

The value must be a string that matches the CSS <color> production, defining a suggested color that user agents should use to customize the display of the page or of the surrounding user interface. For example, a browser might color the page's title bar with the specified value, or use it as a color highlight in a tab bar or task switcher.

Within an HTML document, the media attribute value must be unique amongst all the meta elements with their name attribute value set to an ASCII case-insensitive match for theme-color.

This standard itself uses "WHATWG green" as its theme color:

<!DOCTYPE HTML>
<title>HTML Standard</title>
<meta name="theme-color" content="#3c790a">
...

The media attribute may be used to describe the context in which the provided color should be used.

If we only wanted to use "WHATWG green" as this standard's theme color in dark mode, we could use the prefers-color-scheme media feature:

<!DOCTYPE HTML>
<title>HTML Standard</title>
<meta name="theme-color" content="#3c790a" media="(prefers-color-scheme: dark)">
...

When using the theme color in UI, user agents may adjust it in implementation-specific ways to make it more suitable for the UI in question. For example, if a user agent intends to use the theme color as a background and display white text over it, it might use a darker variant of the theme color in that part of the UI, to ensure adequate contrast.

color-scheme

To aid user agents in rendering the page background with the desired color scheme immediately (rather than waiting for all CSS in the page to load), a 'color-scheme' value can be provided in a meta element.

The value must be a string that matches the syntax for the CSS 'color-scheme' property value. It determines the page's supported color-schemes.

There must not be more than one meta element with its name attribute value set to an ASCII case-insensitive match for color-scheme per document.

The following declaration indicates that the page is aware of and can handle a color scheme with dark background colors and light foreground colors:

<meta name="color-scheme" content="dark">

Because these rules check successive elements until they find a match, an author can provide multiple such values to handle fallback for legacy user agents. Opposite to how CSS fallback works for properties, the multiple meta elements needs to be arranged with the legacy values after the newer values.

4.2.5.2 Other metadata names

Anyone can create and use their own extensions to the predefined set of metadata names. There is no requirement to register such extensions.

However, a new metadata name should not be created in any of the following cases:

Also, before creating and using a new metadata name, consulting the WHATWG Wiki MetaExtensions page is encouraged — to avoid choosing a metadata name that's already in use, and to avoid duplicating the purpose of any metadata names that are already in use, and to avoid new standardized names clashing with your chosen name. [WHATWGWIKI]

Anyone is free to edit the WHATWG Wiki MetaExtensions page at any time to add a metadata name. New metadata names can be specified with the following information:

Keyword

The actual name being defined. The name should not be confusingly similar to any other defined name (e.g. differing only in case).

Brief description

A short non-normative description of what the metadata name's meaning is, including the format the value is required to be in.

Specification
A link to a more detailed description of the metadata name's semantics and requirements. It could be another page on the wiki, or a link to an external page.
Synonyms

A list of other names that have exactly the same processing requirements. Authors should not use the names defined to be synonyms (they are only intended to allow user agents to support legacy content). Anyone may remove synonyms that are not used in practice; only names that need to be processed as synonyms for compatibility with legacy content are to be registered in this way.

Status

One of the following:

Proposed
The name has not received wide peer review and approval. Someone has proposed it and is, or soon will be, using it.
Ratified
The name has received wide peer review and approval. It has a specification that unambiguously defines how to handle pages that use the name, including when they use it in incorrect ways.
Discontinued
The metadata name has received wide peer review and it has been found wanting. Existing pages are using this metadata name, but new pages should avoid it. The "brief description" and "specification" entries will give details of what authors should use instead, if anything.

If a metadata name is found to be redundant with existing values, it should be removed and listed as a synonym for the existing value.

If a metadata name is added in the "proposed" state for a period of a month or more without being used or specified, then it may be removed from the WHATWG Wiki MetaExtensions page.

If a metadata name is added with the "proposed" status and found to be redundant with existing values, it should be removed and listed as a synonym for the existing value. If a metadata name is added with the "proposed" status and found to be harmful, then it should be changed to "discontinued" status.

Anyone can change the status at any time, but should only do so in accordance with the definitions above.

4.2.5.3 Pragma directives

When the http-equiv attribute is specified on a meta element, the element is a pragma directive.

The http-equiv attribute is an enumerated attribute with the following keywords and states:

Keyword State Brief description
content-type Encoding declaration An alternative form of setting the charset.
default-style Default style Sets the name of the default CSS style sheet set.
refresh Refresh Acts as a timed redirect.
x-ua-compatible X-UA-Compatible In practice, encourages Internet Explorer to more closely follow the specifications.
content-security-policy Content security policy Enforces a Content Security Policy on a Document.
Encoding declaration state (http-equiv="content-type")

The Encoding declaration state is just an alternative form of setting the charset attribute: it is a character encoding declaration.

For meta elements with an http-equiv attribute in the Encoding declaration state, the content attribute must have a value that is an ASCII case-insensitive match for a string that consists of: the literal string "text/html;", optionally followed by any number of ASCII whitespace, followed by the literal string "charset=utf-8".

A document must not contain both a meta element with an http-equiv attribute in the Encoding declaration state and a meta element with the charset attribute present.

The Encoding declaration state may be used in HTML documents, but elements with an http-equiv attribute in that state must not be used in XML documents.

Default style state (http-equiv="default-style")

Alternative_style_sheets

Support in one engine only.

Firefox3+Safari?Chrome1–48
OperaYesEdgeNo
Edge (Legacy)?Internet Explorer8+
Firefox Android?Safari iOS?Chrome Android?WebView Android?Samsung Internet?Opera Android?

This pragma sets the name of the default CSS style sheet set.

Refresh state (http-equiv="refresh")

This pragma acts as a timed redirect.

A Document object has an associated will declaratively refresh (a boolean). It is initially false.

For meta elements with an http-equiv attribute in the Refresh state, the content attribute must have a value consisting either of:

In the former case, the integer represents a number of seconds before the page is to be reloaded; in the latter case the integer represents a number of seconds before the page is to be replaced by the page at the given URL.

A news organization's front page could include the following markup in the page's head element, to ensure that the page automatically reloads from the server every five minutes:

<meta http-equiv="Refresh" content="300">

A sequence of pages could be used as an automated slide show by making each page refresh to the next page in the sequence, using markup such as the following:

<meta http-equiv="Refresh" content="20; URL=page4.html">
X-UA-Compatible state (http-equiv="x-ua-compatible")

In practice, this pragma encourages Internet Explorer to more closely follow the specifications.

For meta elements with an http-equiv attribute in the X-UA-Compatible state, the content attribute must have a value that is an ASCII case-insensitive match for the string "IE=edge".

User agents are required to ignore this pragma.

Content security policy state (http-equiv="content-security-policy")

This pragma enforces a Content Security Policy on a Document. [CSP]

For meta elements with an http-equiv attribute in the Content security policy state, the content attribute must have a value consisting of a valid Content Security Policy, but must not contain any report-uri, frame-ancestors, or sandbox directives. The Content Security Policy given in the content attribute will be enforced upon the current document. [CSP]

At the time of inserting the meta element to the document, it is possible that some resources have already been fetched. For example, images might be stored in the list of available images prior to dynamically inserting a meta element with an http-equiv attribute in the Content security policy state. Resources that have already been fetched are not guaranteed to be blocked by a Content Security Policy that's enforced late.

A page might choose to mitigate the risk of cross-site scripting attacks by preventing the execution of inline JavaScript, as well as blocking all plugin content, using a policy such as the following:

<meta http-equiv="Content-Security-Policy" content="script-src 'self'; object-src 'none'">

There must not be more than one meta element with any particular state in the document at a time.

4.2.5.4 Specifying the document's character encoding

A character encoding declaration is a mechanism by which the character encoding used to store or transmit a document is specified.

The Encoding standard requires use of the UTF-8 character encoding and requires use of the "utf-8" encoding label to identify it. Those requirements necessitate that the document's character encoding declaration, if it exists, specifies an encoding label using an ASCII case-insensitive match for "utf-8". Regardless of whether a character encoding declaration is present or not, the actual character encoding used to encode the document must be UTF-8. [ENCODING]

The following restrictions also apply:

In addition, due to a number of restrictions on meta elements, there can only be one meta-based character encoding declaration per document.

If an HTML document does not start with a BOM, and its encoding is not explicitly given by Content-Type metadata, and the document is not an iframe srcdoc document, then the encoding must be specified using a meta element with a charset attribute or a meta element with an http-equiv attribute in the Encoding declaration state.

A character encoding declaration is required (either in the Content-Type metadata or explicitly in the file) even when all characters are in the ASCII range, because a character encoding is needed to process non-ASCII characters entered by the user in forms, in URLs generated by scripts, and so forth.

Using non-UTF-8 encodings can have unexpected results on form submission and URL encodings, which use the document's character encoding by default.

If the document is an iframe srcdoc document, the document must not have a character encoding declaration. (In this case, the source is already decoded, since it is part of the document that contained the iframe.)

In XML, the XML declaration should be used for inline character encoding information, if necessary.

In HTML, to declare that the character encoding is UTF-8, the author could include the following markup near the top of the document (in the head element):

<meta charset="utf-8">

In XML, the XML declaration would be used instead, at the very top of the markup:

<?xml version="1.0" encoding="utf-8"?>

4.2.6 The style element

Element/style

Support in all current engines.

Firefox1+Safari1+Chrome1+
Opera3.5+Edge79+
Edge (Legacy)12+Internet Explorer3+
Firefox Android?Safari iOS?Chrome Android?WebView Android?Samsung Internet?Opera Android10.1+
Categories:
Metadata content.
Contexts in which this element can be used:
Where metadata content is expected.
In a noscript element that is a child of a head element.
Content model:
Text that gives a conformant style sheet.
Tag omission in text/html:
Neither tag is omissible.
Content attributes:
Global attributes
media — Applicable media
blocking — Whether the element is potentially render-blocking
Also, the title attribute has special semantics on this element: CSS style sheet set name
Accessibility considerations:
For authors.
For implementers.
DOM interface:
Uses HTMLStyleElement.

The style element allows authors to embed CSS style sheets in their documents. The style element is one of several inputs to the styling processing model. The element does not represent content for the user.

HTMLStyleElement/disabled

Support in all current engines.

Firefox1+Safari1+Chrome1+
Opera12.1+Edge79+
Edge (Legacy)13+Internet Explorer5.5+
Firefox Android?Safari iOS?Chrome Android?WebView Android?Samsung Internet?Opera Android12.1+

The disabled getter steps are:

  1. If this does not have an associated CSS style sheet, return false.

  2. If this's associated CSS style sheet's disabled flag is set, return true.

  3. Return false.

The disabled setter steps are:

  1. If this does not have an associated CSS style sheet, return.

  2. If the given value is true, set this's associated CSS style sheet's disabled flag. Otherwise, unset this's associated CSS style sheet's disabled flag.

Importantly, disabled attribute assignments only take effect when the style element has an associated CSS style sheet:

const style = document.createElement('style');
style.disabled = true;
style.textContent = 'body { background-color: red; }';
document.body.append(style);
console.log(style.disabled); // false

The media attribute says which media the styles apply to. The value must be a valid media query list.

The default, if the media attribute is omitted, is "all", meaning that by default styles apply to all media.

The blocking attribute is a blocking attribute.

Alternative_style_sheets

Support in one engine only.

Firefox3+Safari?Chrome1–48
OperaYesEdgeNo
Edge (Legacy)?Internet Explorer8+
Firefox Android?Safari iOS?Chrome Android?WebView Android?Samsung Internet?Opera Android?

The title attribute on style elements defines CSS style sheet sets. If the style element has no title attribute, then it has no title; the title attribute of ancestors does not apply to the style element. If the style element is not in a document tree, then the title attribute is ignored. [CSSOM]

The title attribute on style elements, like the title attribute on link elements, differs from the global title attribute in that a style block without a title does not inherit the title of the parent element: it merely has no title.

The child text content of a style element must be that of a conformant style sheet.

A style element is implicitly potentially render-blocking if the element was created by its node document's parser.


This specification does not specify a style system, but CSS is expected to be supported by most web browsers. [CSS]

The LinkStyle interface is also implemented by this element. [CSSOM]

The following document has its stress emphasis styled as bright red text rather than italics text, while leaving titles of works and Latin words in their default italics. It shows how using appropriate elements enables easier restyling of documents.

<!DOCTYPE html>
<html lang="en-US">
 <head>
  <title>My favorite book</title>
  <style>
   body { color: black; background: white; }
   em { font-style: normal; color: red; }
  </style>
 </head>
 <body>
  <p>My <em>favorite</em> book of all time has <em>got</em> to be
  <cite>A Cat's Life</cite>. It is a book by P. Rahmel that talks
  about the <i lang="la">Felis catus</i> in modern human society.</p>
 </body>
</html>