HTML Basic - Chapter4

HTML Elements

　　　　An HTML element usually consists of a start tag and end tag, with the content inserted in between:<tagname>Content goes here...</tagname>

　　　　The HTML element is everything from the start tag to the end tag:<p>My first paragraph.</p>

　　　　Some HTML elements are empty (have not content) and do not have an end tag, such as the <br> element (which indicates a line break).

　　Nested HTML Elements

　　　　HTML elements can be nested (elements can contain elements).

　　　　All HTML documents consist of nested HTML elements.

　　　　This example contains four HTML elements:

　　　　Example

　　　　　　<!DOCTYPE html>

　　　　　　<html>

　　　　　　<body>

　　　　　　<h1>My First Heading</h1>

　　　　　　<p>My first paragraph.</p>

　　　　　　</body>

　　　　　　</html>

　　Example Explained

　　　　The <html> element defines the whole document.

　　　　It has a start tag <html> and an end tag </html>.

　　　　The element content is another HTML element (the <body> element)

　　　　　　<html>

　　　　　　<body>

　　　　　　<h1>My First Heading</h1>

　　　　　　<p>My first paragraph.<p>

　　　　　　</body>

　　　　　　</html>

　　　　The <body> element defines the document body.

　　　　It has a start tag <body> and an end tag </body>.

　　　　The element content is two other HTML elements (<h1> and <p>)

　　　　The <h1> element defines a heading.

　　　　It has a start tag <h1> and an end tag </h1>.

　　　　The element content is: My First Heading.

　　　　The <p> element defines a paragraph.

　　　　It has a start tag <p> and an end tag </p>

　　　　The element content is: My first paragraph.

　　Do Not Forget the End Tag

　　Empty HTML Elements

　　　　HTML elements with not content are called empty elements.

　　　　<br> is an empty element without a closing tag (the <br> tag defines a line break).

　　　　Empty elements can be "closed" in the opening tag like this: <br />.

　　　　HTML5 does not require empty elements to be closed. But if you want stricter validation, or if you need to make your document readable by XML parsers, you must close all HTML element properly.

　　User Lowcase Tags

　　　　HTML tags are not case sensitive: <P> means the same as <p>.

　　　　The HTML5 standard does not require lowcase tags, but W3C recommends lowcase in HTML, and demands lowercase for stricter document types like XHTML.

posted on 2016-08-01 12:41 lostkite 阅读(181) 评论(0) 收藏举报