If you haven’t already heard about it, schema.org provides a method to give additional semantic meaning to your markup. One of the benefits to using microdata on your markup is the possibility of a rich snippet being displayed on a search engine’s results page.

Here is how an address could be marked up with HTML:

And the styles applied to it:

.address { font-weight: bold; }
.address em { font-style: normal; color: orange; }

Results in the following:

This is how microdata can be applied using the above example:

The idea here is nothing new. Microformats such has hCard and hRecipe have been around for some time. One of the things that sets schema.org apart from the others is wide variety of objects it supports. Read more information at schema.org to get started!