Traditionally, HTML describes the structure of a document but doesn't say much about the meaning of the content. A microformat is a way of using standard HTML elements and class attributes to build meaning into the document. Visit http://microformats.org for the full scoop.

Simple, open, need-driven data formats can define all manner of people, places and things. Not only are they human-viewable, but human-writable as well. Imagine posting "things I want" and "things I'm selling" lists on your blog as microformats, allowing all manner of services to fulfill your requests. See: microformats.org

Microformats are markup that allow expression of semantics in an HTML (or XHTML) web page. Programs can extract meaning from a web page that is marked up with microformats.