What is Zen Coding ?

Answer:

Zen Coding is an editor plugin for high-speed HTML, XML, XSL (or any other structured code format) coding and editing.

The core of this plugin is a powerful abbreviation engine which allows you to expand expressions—similar to CSS selectors—into HTML code. In other word, you can say A faster way to write HTML way to write HTML using a CSS style selector syntax.

Now, you can it in Visual Studio 2012 via the Web Essentials 2012 plug in (v1.7).
It become a great way to write monotonous HTML much more efficiently.

e.g:

div#page>div.logo+ul#navigation>li*5>a
..can be expanded into:

<div id="page">
<div class="logo"></div>
<ul id="navigation">
<li><a href=""></a></li>
<li><a href=""></a></li>
<li><a href=""></a></li>
<li><a href=""></a></li>
<li><a href=""></a></li>
</ul>
</div>