Microformats are a set of simple, open data formats that are built upon existing standards. Firefox 3 includes a new microformats API that can be used to build add-ons, but they are otherwise not currently exposed through the Firefox 3 user interface.
For more, see IBM’s new tutorial about how to use the new microformats API in Firefox 3 extensions, and Where are the microformats in Firefox 3? by Mike Kaply.
