Table 
<table>
	<caption></caption>
	<colgroup>
		<col>
		<col>
	</colgroup>
	<thead>
		<tr>
			<th></th>
			<th></th>
		</tr>
	</thead>
	<tfoot>
		<tr>
			<td></td>
			<td></td>
		</tr>
	</tfoot>
	<tbody>
		<tr>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td></td>
			<td></td>
		</tr>
	</tbody>
</table>
HTML entities 
ResultDescriptionEntity NameEntity Number
non-breaking space&nbsp;&#160;
<Less Than Sign&lt;&#60;
>Greater Than Sign&gt;&#62;
HTML5 Page Structure 
<!DOCTYPE HTML>

<html>

<head>
	<meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
	<title>Your Website</title>
</head>

<body>

	<header>
		<nav>
			<ul>
				<li>Your menu</li>
			</ul>
		</nav>
	</header>
	
	<section>
	
		<article>
			<header>
				<h2>Article title</h2>
				<p>Posted on <time datetime="2009-09-04T16:31:24+02:00">September 4th 2009</time> by <a href="#">Writer</a> - <a href="#comments">6 comments</a></p>
			</header>
			<p>Pellentesque habitant morbi tristique senectus et netus et malesuada fames ac turpis egestas.</p>
		</article>
		
		<article>
			<header>
				<h2>Article title</h2>
				<p>Posted on <time datetime="2009-09-04T16:31:24+02:00">September 4th 2009</time> by <a href="#">Writer</a> - <a href="#comments">6 comments</a></p>
			</header>
			<p>Pellentesque habitant morbi tristique senectus et netus et malesuada fames ac turpis egestas.</p>
		</article>
		
	</section>

	<aside>
		<h2>About section</h2>
		<p>Donec eu libero sit amet quam egestas semper. Aenean ultricies mi vitae est. Mauris placerat eleifend leo.</p>
	</aside>

	<footer>
		<p>Copyright 2009 Your name</p>
	</footer>

</body>

</html>
Left & Right Halves Layout
* { margin: 0; padding: 0; }
#pagewrap {width:100%; position:relative;}
#left { position: absolute; left: 0; top: 0; width: 50%; }
#right { position: absolute; right: 0; top: 0; width: 50%; }
<div id="pagewrap">
    <div id="left">
        <p>Left Half</p>
        <p>test</p>
        <p>test</p>
    </div>

    <div id="right">
        <p>Right Half</p>
        <p>test</p>
        <p>test</p>
    </div>
</div>
Responsive Meta Tag
<meta name="viewport" content="width=device-width">
OR
<meta name="viewport" content="width=device-width, initial-scale=1">