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/HTML

<meta>

The HTML <meta> element represents any metadata information that cannot be represented by one of the other HTML meta-related elements (<base>, <link>, <script>, <style> or <title>).

Content categories	Metadata content. If the `itemprop` attribute is present: flow content, phrasing content.
Permitted content	None, it is an empty element.
Tag omission	As it is a void element, the start tag must be present and the end tag must not be present
Permitted parents	`<meta charset>`, `<meta http-equiv>`: a `<head>` element. If the `http-equiv` is not an encoding declaration, it can also be inside a `<noscript>` element, itself inside a `<head>` element.
Permitted ARIA roles	None
DOM interface	`HTMLMetaElement`

Attributes

This element includes the global attributes.

Note that the global name has a specific semantic in the <meta> element and that the itemprop must not be set when one of the name, http-equiv or charset is already used.

charset

This attribute declares the character encoding used of the page. It can be locally overridden using the lang attribute on any element. This attribute is a literal string and must be one of the preferred MIME names for a character encoding as defined by the IANA. Though the standard doesn't request a specific character encoding, it gives some recommendations:

Authors are encouraged to use UTF-8.
Authors should not use ASCII-incompatible encodings (i.e. those that don't map the 8-bit code points 0x20 to 0x7E to the Unicode 0x0020 to 0x007E code points) as these represent a security risk: browsers not supporting them may interpret benign content as HTML Elements. This is the case of at least the following charsets: JIS_C6226-1983, JIS_X0212-1990, HZ-GB-2312, JOHAB, the ISO-2022 family, and the EBCDIC family.
Authors must not use CESU-8, UTF-7, BOCU-1 and SCSU, also falling in that category and not intended to be used on the web. Cross-scripting attacks with some of these encodings have been documented.
Authors should not use UTF-32 because not all HTML5 encoding algorithms can distinguish it from UTF-16.

Notes:

The declared character set must match the one of the page. There is no valid reason to declare an inaccurate character set.
This <meta> element must be inside the <head> element and within the 1024 first bytes of the page, as some browsers only look at these first bytes before choosing a character set for the page.
This <meta> element is only a part of the algorithm to determine the character set of a page that browsers apply. The HTTP Content-Type header and any BOM elements have precedence over this element.
It is good practice, and strongly recommended, to define the character set using this attribute. If no character set is defined for a page, several cross-scripting techniques may be able to harm the page user, such as the UTF-7 fallback cross-scripting technique. Always setting this meta will protect against these risks.
This <meta> element is a synonym for the pre-HTML5 <meta http-equiv="Content-Type" content="text/html; charset=IANAcharset"> where IANAcharset corresponds of the value of the equivalent charset attribute. This syntax is still allowed, although obsolete and no longer recommended.

content

This attribute gives the value associated with the http-equiv or name attribute, depending on the context.

http-equiv

This enumerated attribute defines the pragma that can alter servers and user-agents behavior. The value of the pragma is defined using the content and can be one of the following:

"content-language" deleted

This pragma defines the default language of the page.

Do not use this pragma, as it is obsolete. Use the global lang attribute on the <html> element instead.

"Content-Security-Policy"

This value allows web site administrators to define content policies for served resources. With a few exceptions, policies mostly involve specifiying server origins and script endpoints. This helps guard against cross-site scripting attacks.

"content-type" deleted

This attribute defines the MIME type of the document, eventually followed by its character set. It follows the same syntax as the HTTP content-type entity-header field, but as it is inside an HTML Element, most values are not possible. Therefore the valid syntax for its content is the literal string 'text/html' eventually followed by a character set with the following syntax:'; charset=IANAcharset' where IANAcharset is the preferred MIME name for a character set as defined by the IANA.

Usage note:

Do not use this pragma as it is obsolete. Use the charset attribute on the <meta> element instead.
As the <meta> may not be used to change the type of a document in an XHTML document, or in an HTML5 document following the XHTML syntax, never set MIME type to an XHTML MIME type that way. It would be incorrect.
Only an HTML document can use the content-type, so most of it is redundant: that's why it has been obsoleted and replaced by the charset attribute.

"default-style"

This pragma specifies the preferred stylesheet to be used on the page. The content attribute must contain the title of a <link> element whose href attribute links to a CSS stylesheet, or the title of a <style> element which contains a CSS stylesheet.

"refresh"

This pragma specifies:

the number of seconds until the page should be reloaded, if the content attribute contains only a positive integer number;
the number of seconds until the page should be redirected to another, if the content attribute contains a positive integer number followed by the string ';url=' and a valid URL.

"set-cookie" deleted

This pragma defines a cookie for the page. Its content must follow the syntax defined in the IETF HTTP Cookie Specification.

Note: Do not use this pragma as it is obsolete. Use the HTTP header set-cookie instead.

name

This attribute defines the name of document-level metadata. It should not be set if one of the attributes itemprop, http-equiv or charset is also set.
This document-level metadata name is associated with a value, contained by the content attribute. The possible values for the name element are, with their associated value, stored via the content attribute:

application-name, defining the name of the web application running in the webpage;
Note:
- Browsers may use this to identify the application. It is different from the <title> element, which usually consist of the application name but may also contain specific information like the document name or a status;
- Simple webpages shouldn't define the application-name meta.
author, defining, in a free format, the name of the author of the document;
description, containing a short and accurate summary of the content of the page. Several browsers, among them Firefox and Opera, use this meta as the default description of the page when bookmarked;
generator, containing, in a free format, the identifier to the software that generated the page;
keywords, containing, as strings separated by commas, relevant words associated with the content of the page;

referrer controlling the content of the HTTP Referer HTTP header attached to any request sent from this document:

Values for the content attribute of <meta name="referrer">
`no-referrer`	Do not send a HTTP `Referer` header.
`origin`	Send the origin of the document.
`no-referrer-when-downgrade`	Send the origin as referrer to a-priori as-much-secure destination (https->https), but doesn't send a referrer to a less secure destination (https->http). This is the default behavior.
`origin-when-crossorigin`	Send a full URL (stripped from parameters) when performing a same-origin request, but only send the origin of the document for other cases.
`unsafe-URL`	Send a full URL (stripped from parameters) when perfoming a a same-origin or cross-origin request.

Note: Some browsers support keywords always, default, and never for referrer. These values are deprecated.

Note: Dynamically inserting <meta name="referrer"> (by document.write or appendChild) create a non-determinism when it comes to sending referrers or not. Note also that when several conflicting policies are defined, the No-referrer policy is applied.

The attribute may also have a value taken from the extended list defined on WHATWG Wiki MetaExtensions page. Although none have been formally accepted yet, a few commonly used names are among the proposals:

creator, defining, in a free format, the name of the creator of the document. Note that it can be the name of the institution. If there are more than one, several <meta> elements should be used;
googlebot, which is a synonym of robots, but is only followed by Googlebot, the indexing crawler for Google;
publisher, defining, in a free format, the name of the publisher of the document. Note that it can be the name of the institution;

robots, defining the behavior that cooperative crawlers should have with the page. It is a comma-separated list of values from the following list:

Values for the content of <meta name="robots">
Value	Description	Used by
`index`	Allows the robot to index the page	All
`noindex`	Prevents the robot from indexing the page	All
`follow`	Allows the robot to follow the links on the page	All
`nofollow`	Prevents the robot from following the links on the page	All
`noodp`	Prevents the usage of the Open Directory Project description, if any, as the description of the page in the search engine results page	Google, Yahoo, Bing
`noarchive`	Prevents the search engine from caching the content of the page	Google, Yahoo
`nosnippet`	Prevents the display of any description of the page in the search engine results page	Google
`noimageindex`	Prevents this page from appearing as the referring page of an indexed image	Google
`nocache`	Synonym of `noarchive`	Bing

Notes:

Only cooperative robots will follow the rules defined by the robots name. Do not expect to keep e-mail harvesters at bay with this.
The robot still needs to access the page in order to read the meta value. If you want to keep them at bay, for example to prevent bandwidth consumption, use a robots.txt file instead (or in complement).
If you want to remove the page of an index, changing the meta to noindex will work, but only when the robot visits the page again. Ensure that the robots.txt file is not preventing such visits. Some search engines have developer's tools, allowing a quick removal of some page.
Some possible values are mutually exclusive, like using index and noindex, or follow and nofollow, at the same time. In these cases the behavior of the robot is undefined, and may vary from one to the other. So avoid these cases.
Some search engine crawler robots, like those of Google, Yahoo Search or Bing, support the same values on an HTTP directive, X-Robot-Tags: this allows them to use these pragma on non-HTML documents, like images.

slurp, which is a synonym of robots, but is only followed by Slurp, the indexing crawler for Yahoo Search;

Finally a few names are in common use, though not in the process of being standardized:

viewport, which gives hints about the size of the initial size of the viewport. This pragma is used by several mobile devices only.

Values for the content of `<meta name="viewport">`
Value	Possible values	Description
`width`	a positive integer number or the literal `device-width`	defines the width, in pixels, of the viewport
`height`	a positive integer number or the literal `device-height`	defines the height, in pixels, of the viewport
`initial-scale`	a positive number between `0.0` and `10.0`	defines the ratio between the device width (`device-width` in portrait mode or `device-height` in landscape mode) and the viewport size.
`maximum-scale`	a positive number between `0.0` and `10.0`	defines the maximum value of the zoom; it must be greater or equal to the `minimum-scale` or the behavior is indeterminate.
`minimum-scale`	a positive number between `0.0` and `10.0`	defines the minimum value of the zoom; it must be smaller or equal to the `maximum-scale` or the behavior is indeterminate.
`user-scalable`	a boolean value (`yes` or `no`)	If set to `no`, the user is not able to zoom in the webpage. Default value is `yes`.

Specification	Status	Comment
CSS Device Adaptation The definition of '<meta name="viewport">' in that specification.	Working Draft	Non-normatively describes the Viewport META element

Notes

Depending on the attributes set, the kind of metadata can be one of the following:

If name is set, it is document-level metadata, applying to the whole page.
If http-equiv is set, it is a pragma directive, i.e. information normally given by the web server about how the web page should be served.
If charset is set, it is a charset declaration, i.e. the charset used for the serialized form of the webpage.
If itemprop is set, it is user-defined metadata, transparent for the user-agent as the semantics of the metadata is user-specific.

Examples

<!-- In HTML5 -->
<meta charset="utf-8">

<!-- Redirect page after 3 seconds -->
<meta http-equiv="refresh" content="3;url=https://www.mozilla.org/">

Specifications

Specification	Status	Comment
Referrer Policy The definition of '<meta name="referrer">' in that specification.	Working Draft	Defines values and semantics of `<meta name="referrer">`.
WHATWG HTML Living Standard The definition of '<meta>' in that specification.	Living Standard	Added `itemprop` attribute
HTML5 The definition of '<meta>' in that specification.	Recommendation	Added `charset` attribute
HTML 4.01 Specification The definition of '<meta>' in that specification.	Recommendation

Browser compatibility

Feature	Chrome	Edge	Firefox (Gecko)	Internet Explorer	Opera	Safari
Basic support	(Yes)	(Yes)	1.0 (1.7 or earlier)	(Yes)	(Yes)	(Yes)
`name="referrer"`	17	?	36.0 (36.0) [1]	?	?	?
Constrained to values listed under referrer (as specified in the spec.)	46.0

Feature	Android	Android Webview	Edge	Firefox Mobile (Gecko)	IE Mobile	Opera Mobile	Safari Mobile	Chrome for Android
Basic support	(Yes)	(Yes)	(Yes)	1.0 (1.0)	(Yes)	(Yes)	(Yes)	(Yes)
`name="referrer"`	?	(Yes)	?	36.0 (36.0) [1]	?	?	?	(Yes)
Constrained to values listed under referrer (as specified in the spec.)	No support	46.0	?	?	?	?	?	46.0