<! Doctype> Label
Definitions and usage
<! The doctype> declaration must be in the first line of the HTML 5 document, before the <html> label. The label tells the HTML specification used by the browser's document.
DOCTYPE declaration does not belong to HTML tags; It is an instruction that tells the browser the version of the markup used to write the page.
It is important to specify DOCTYPE in all HTML documents so that the browser can understand the expected document type.
DOCTYPE in HTML 4.01 need to refer to DTDs because HTML 4.01 is based on SGML. While HTML 5 is not based on SGML, there is no need to refer to DTDs, but DOCTYPE is needed to regulate the behavior of browsers (let browsers run the way they should). ）。
Instance
HTML 5 document with the correct document type (DOCTYPE):
<! DOCTYPE html>
<html>
<head>
<title>title of the Document</title>
</head>
<body>
The content of the document ...
</body>
</html>
Try the following code yourself.
<! DOCTYPE html>
<html>
<head>
<title>title of the Document</title>
</head>
<body>
The content of the document ...
</body>
</html>
Differences between HTML 4.01 and HTML 5
There are 3 different document types in HTML 4.01, and only one in HTML 5:
<! DOCTYPE html>
In HTML 5, document type declarations are not straightforward.
Tips and Comments:
Note: <! doctype> tag has no end tag!
Hint: <! Doctype> is not sensitive to case.
Property
NONE
Definitions and usage
<a> label defines hyperlinks for linking from one page to another.
The most important attribute of the <a> element is the href attribute, which specifies the target of the link.
In all browsers, the default appearance of the link is:
Links that are not accessed are underlined and blue
Links that have been accessed are underlined and purple
Active links are underlined and red
Instance
Link to Sina:
<a href= "http://www.sina.com.cn" >Sina</a>
Try it for yourself.
<! DOCTYPE html>
<html>
<body>
<a href= "http://www.sina.com.cn" >visit sina.com.cn!</a>
</body>
</html>
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