a third option developed using lessons learned from microformats and RDFa, and designed to be integrated into HTML5 itself: microdata.

“Adding microdata” to your page is a matter of adding a few attributes to the HTML elements you already have.

So where is the real information? It’s in the <dd> element, so that’s where we need to put the itemprop attribute. Which property is it? It’s the name property. Where is the property value? It’s the text within the <dd> element. Does that need to be marked up? the HTML5 microdata data model says no, <dd> elements have no special processing, so the property value is just the text within the element.

The HTML5 microdata standard includes both HTML markup (primarily for search engines) and a set of DOM functions (primarily for browsers). There’s no harm in including microdata markup in your web pages. It’s nothing more than a few well-placed attributes, and search engines that don’t understand the microdata attributes will just ignore them. But if you need to access or manipulate microdata through the DOM, you’ll need to check whether the browser supports the microdata DOM API.

A weblog-style <article> A published date leads us to add a <header>, and there’s also content that would be suitable in a <footer> elements. <article>  <header>    <h1>Apple</h1>    <p>Published: <time pubdate="pubdate">2009-10-09</time></p>  </header>  <p>The <b>apple</b> is the pomaceous fruit of the apple tree...</p>  ...  <footer>    <p><small>Creative Commons Attribution-ShareAlike License</small></p>  </footer></article>

There is a boolean attribute pubdate specifically for this

<time datetime="2010-01-20" pubdate>

To see an example of the <footer> within an article/section look no further than this very page.

<article>   Article content appears here.   <footer>   Footer information for article.   </footer></article>

Breadcrumbs Again, I would say yes to this as well. Although breadcrumbs are not always necessary and can be used when not applicable, on large sites a breadcrumb trail can be an important navigation aid.

How to transfer the default code to html5? Here it is: open the functions.php (you can find it in the theme folder), then copy and paste the following php code to the functions.php

Look up HTML5, CSS3, etc features, know if they are ready for use, and if so find out how you should use them – with polyfills, fallbacks or as they are.