Example Explained

<tagname>content</tagname>

HTML Elements

"HTML tags" and "HTML elements" are often used to describe the same thing.
But strictly speaking, an HTML element is everything between the start tag and the end tag, including the tags:
HTML Element:
<p>This is a paragraph.</p>

HTML Page Structure

Below is a visualization of an HTML page structure:
<html>
<body>
<h1>This a heading</h1>
<p>This is a paragraph.</p>
<p>This is another paragraph.</p>
</body>
</html>

HTML Versions

Since the early days of the web, there have been many versions of HTML:
VersionYear
HTML1991
HTML+1993
HTML 2.01995
HTML 3.21997
HTML 4.011999
XHTML 1.02000
HTML52012
XHTML52013


The <!DOCTYPE> Declaration

The <!DOCTYPE> declaration helps the browser to display a web page correctly.
There are many different documents on the web, and a browser can only display an HTML page 100% correctly if it knows the HTML type and version used.

Common Declarations

HTML5

<!DOCTYPE html>

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"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
For a complete list of document type declarations, go to our DOCTYPE Reference.