HTML

add <!DOCTYPE> declaration so the browser knows what type of document to expect and how to interpret it.

HTML 5

<!DOCTYPE html>

HTML 5 requires a DOCTYPE to be specified to ensure that the browser renders the page in standards mode.

HTML 4

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

HTML namespace declaration:

<html xmlns="http://www.w3.org/1999/xhtml" 
 xml:lang="en" lang="en" />

specify character encoding:

<head> 
 <meta http-equiv="content-type" 
 content="text/html;charset=UTF-8" />

HTML is the publishing language for describing the structure of web pages. HTML and CSS are two of the core technologies for building web pages, HTML for structured content and CSS for layout and presentation.

<html>
<head>
<title>design</title>
</head>
<body>
<h1>Design</h1>
<p>clean and simple</p>
<img src="/img/beautiful.png" alt="beautiful design" />
<a href="/beautiful/" title="beautiful place">select</a>
<a href="mailto:u@abc.com?subject=here%20and" title="contact">send</a>
</body>
</html>