What are Microformats?

Every few months I see a burp in the world of microformats – here’s some more details:

Microformats are quick-and-dirty standards for expressing common data types. The standard example is a microformat for reviews which lets a blogger encode the expected data name of the reviewed thing, number of stars, commentary, etc. in a standard way so another app can harvest it and, perhaps, aggregate all the reviews of restaurants in Watertown. Microformats are developed quickly, using what’s out there as a starting point, aiming at usable but probably incomplete standards, as opposed to setting up an industry committee to argue for 12 years about what Platonic ideal of the standard.