What does doctype html mean?-Common Problem-php.cn

What does doctype html mean?

青灯夜游

Release： 2023-03-06 14:56:05

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"doctype html" refers to the html5 standard web page declaration, which tells the browser that the current HTML is written in the fifth version, and the complete syntax is "<!DOCTYPE HTML>". The doctype declaration is an instruction that must be located on the first line in the HTML5 document, that is, before the "" tag.

What does doctype html mean?

The operating environment of this tutorial: Windows 7 system, CSS3&&HTML5 version, Dell G3 computer.

"doctype html" refers to the html5 standard web page declaration, which tells the browser that the current HTML is written in version 5.

HTML5 DOCTYPE declaration

DOCTYPE is the abbreviation of document type.

The doctype declaration is not an HTML tag; rather, it is a document type tag, which is an instruction that tells the browser the version of markup in which the page was written.

The doctype declaration is a document type declaration in a standard universal markup language. It is used in web design to indicate what version of XHTML or HTML you are using.

html5 There is only one doctype declaration:

<!DOCTYPE HTML>

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The declaration must be located on the first line in the HTML5 document, that is, before the tag. This tag tells the browser the HTML specification used by the document.

<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<title>文档标题</title>
</head>

<body>
文档内容......
</body>

</html>

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It is very important to specify the doctype in all HTML documents so that the browser understands the expected document type.

Explanation:

tag has no closing tag.
is not case sensitive.

Extended knowledge: Common other DOCTYPE declarations

HTML 4.01 Strict (strict)

This DTD contains all HTML elements and attributes, but does not include presentational or obsolete elements (such as font). Framesets are not allowed.

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN" "http://www.w3.org/TR/html4/strict.dtd">

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HTML 4.01 Transitional

This DTD contains all HTML elements and attributes, including presentational or obsolete elements (such as font). Framesets are not allowed.

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">

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HTML 4.01 Frameset

This DTD is the same as HTML 4.01 Transitional, but allows the use of frameset content.

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Frameset//EN" "http://www.w3.org/TR/html4/frameset.dtd">

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XHTML 1.0 Strict

This DTD contains all HTML elements and attributes, but does not include presentational or obsolete elements (such as font). Framesets are not allowed. The structure must be written in standard format XML.

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">

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XHTML 1.0 Transitional

This DTD contains all HTML elements and attributes, including presentational or obsolete elements (such as font). Framesets are not allowed. The structure must be written in standard format XML.

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">

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XHTML 1.0 Frameset

This DTD is the same as XHTML 1.0 Transitional, but allows the use of frameset content.

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Frameset//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-frameset.dtd">

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XHTML 1.1

This DTD is the same as XHTML 1.0 Strict, but allows you to add modules (such as ruby support for East Asian languages).

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.1//EN" "http://www.w3.org/TR/xhtml11/DTD/xhtml11.dtd">

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Recommended tutorial: "html video tutorial"

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