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Does html5 require a document type declaration?

青灯夜游Original: 2021-12-22 14:04:592792browse

html5 requires a document type declaration. The DOCTYPE document type declaration helps correctly identify and display web pages in the browser. If the DOCTYPE document type declaration is missing, it will affect whether the CSS style takes effect; therefore, in order for the CSS style sheet to take effect, the DOCTYPE declaration is essential.

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

Statement: is a standard universal markup language document type declaration that helps display web pages correctly in browsers. Because there are many different types of files on the web, HTML versions need to be declared correctly so that browsers can correctly identify and display your page content.

For the CSS style sheet to take effect, the DOCTYPE statement is necessary. The DOCTYPE of the web page in the previous TABLE layout may be omitted and it can be displayed normally. But in the DIV CSS layout, although DOCTYPE is just a piece of code, it is very important, affecting whether the CSS style takes effect. Without the DOCTYPE html declaration, some CSS styles are still valid, but some CSS styles are invalid. So DOCTYPE is essential.

The doctype declaration is case-insensitive, and the following methods can be used:

<!DOCTYPE html>
<!DOCTYPE HTML>
<!doctype html>
<!Doctype Html>

General declaration:

HTML5

<!DOCTYPE html> <!--推荐使用 简单明了-->

HTML 4.01

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

XHTML 1.0

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" 2 "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">

Note:

statement must be placed on the first line of the HTML document

Pay special attention to the statement that it is not an HTML tag

Web page encoding setting

When the web page is displayed with garbled characters, in

< ;/head> Add between tags:

<meta charset="UTF-8"> <!--设置编码为UTF-8-->

Note: Commonly used encodings are: utf-8, gb2312, gbk and other encodings

Does html5 require a document type declaration?

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