This element has a start tag <html> and an end tag </html>.
The content of the element is another HTML element (body element).
Don’t forget the closing tag
Even if you forget to use the closing tag, most browsers will do it correctly Display HTML:
<p>这是一个段落
<p>这是一个段落
The above example can also be displayed normally in the browser because the closing tag is optional. But don’t rely on this approach. Forgetting to use a closing tag can produce unpredictable results or errors.
HTML Empty Element
An HTML element with no content is called Empty element. Empty elements are closed in the opening tag.
<br> It is an empty element without a closing tag (<br> tag definition wraps).
In XHTML, XML, and future versions of HTML, all elements must be closed.
Adding a slash in the opening tag, such as <br />, is the correct way to close an empty element, and is accepted by HTML, XHTML, and XML.
Even though <br> is valid in all browsers, using <br /> is actually a longer-term guarantee.
HTML Tip: Use lowercase tags H
HTML tags are not case-sensitive: <P> is equivalent to <p>. Many websites use uppercase HTML tags.
W3CSschool uses lowercase tags because the World Wide Web Consortium (W3C) recommends lowercase in HTML 4 and will make it mandatory in future versions of (X)HTML.