Microformats: Designed for humans first and machines second, microformats are a set of simple, open data formats built upon existing and widely adopted standards. Instead of throwing away what works today, microformats intend to solve simpler problems first by adapting to current behaviors and usage patterns (e.g. XHTML, blogging).

Microformats are a fairly new 'invention' (just celebrated their first year anniversary) started by Tantek Celik which are, simply put, a specific way of marking up HTML. This specific way of marking up HTML allows for the conversion of websites in to various widely adopted standards which are found in the desktop world via a few easy to use rules. These rules are in the form of class names, rel attributes and abbreviation convention.

There are numerous existing Microformats, including hCard, hCalendar, rel-tag and hAtom. More information on existing and proposed formats can be found on the Microformats Wiki

hCalendar is a simple, open, distributed calendaring and events format, based on the iCalendar standard (RFC2445), suitable for embedding in XHTML, Atom, RSS, and arbitrary XML.

hCard is a simple, open, distributed format for representing people, companies, organizations, and places, using a 1:1 representation of the properties and values of the vCard standard (RFC2426)

Marking up your HTML websites with these formats allows information to be converted to existing formats. For example, hCalendar can be converted for use in iCal, Outlook, Google Calendar / any respectable calendar program and hCards can be imported in to Apple's "Address Book" or Outlook.

You can easily add hCards to contact pages. As long as you've got a name (whether it be a person or company name) then you can create a hCard. However, if more information is available, this makes the hCard a lot more worthwhile. Other information which can be added includes a URL to a website, email address, company name and telephone number. hCards could be added to sentances which talk about a person, such as on an about page. Jeremy Keith has an article called Natural language hCard which discusses how to create a hCard from a simple person-descriptive sentance.

If you're interested in Microformats, or you can't see the point of them yet. Install the Firefox extension called Tails. This finds Microformats on a page and shows you what they are. OK, it doesn't convert them in to a usable format but it just shows the basic premise of extracting this information/data. However, if you come across any websites which are using hAtom, then try running them through some hAtom/Atom converters and putting them in your favourite feed aggregator. This means there isn't a need to duplicate content as external RSS/Atom XML files, you can simply produce one HTML page.

Other websites which are making use of Microformats include Dan Cederholm's wine-rating website Cork'd, which uses hReview and hCards on profile pages.

Yahoo! are doing some cool stuff by adding Microformats to their vast amount of data on their local service.

Yahoo! Local fully supports the hCalendar, hCard, and hReview microformats on almost all business listings, search results, events, and reviews.

Tantek Celik and the team at Technorati have been cooking up a Microformats Search in their kitchen.

We launched the first implementation that indexes and searches posts tagged with rel-tag. We support XOXO for lists and outlines throughout the site, our member's favorite blogs are tagged with xFolk, and plenty of hCard contacts are published in our contact, staff, and profiles pages. We have hCard to vCard and hCalendar to iCalendar converter services so that anyone who publishes their contacts and events on the Web can easily provide "Add to Address Book" and "Add to Calendar" functionality for desktop applications.

There is a lot of interest in Microformats, and if you're interested in web development I seriously urge you to check it out.