In html5, the document type declaration is a DOCTYPE declaration, and the syntax is "". The DOCTYPE declaration is a standard universal markup language document type declaration that allows browsers to understand the HTML specification being used by an HTML5 document.
The operating environment of this tutorial: Windows 7 system, HTML5 version, Dell G3 computer.
In html5, the document type declaration is the DOCTYPE declaration.
The DOCTYPE declaration is a standard universal markup language document type declaration that allows the browser to understand the HTML specification being used by the HTML5 document.
The DOCTYPE declaration is the starting point of the HTML5 document, which means it must be located on the first line of the HTML5 document, before the tag. The
<!DOCTYPE> declaration is not an HTML tag; it is used to tell the web browser which version of HTML is used for the page.
In HTML 4.01, the <!DOCTYPE> declaration needs to reference the DTD (Document Type Declaration) because HTML 4.01 is based on SGML (Standard Generalized Markup Language). DTD specifies the rules of the markup language to ensure that the browser can render the content correctly.
HTML5 is not based on SGML and therefore does not require DTD reference.
Tip: Always add the <!DOCTYPE> declaration to your HTML document to ensure the browser knows the document type in advance.
HTML 4.01 specifies three different <!DOCTYPE> declarations: Strict, Transitional, and Frameset. Only one type is specified in HTML5:
<!DOCTYPE html>
Example: Basic document structure
<!DOCTYPE html>文档标题 文档内容......
Note:
<!DOCTYPE> The tag has no closing tag.
<!DOCTYPE> Declarations are not case-sensitive.
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