By erigena, published 19th October 2006.
What are Microformats?
Microformats are markup that allow expression of semantics in an HTML document. Microformats are designed for humans first and machines second, and are a set of simple, open data formats built upon existing and widely adopted web standards.
- Microformats are easy conventions for marking up data on the Web
- Microformats are used as solutions to specific common problems.
- explicitly encourage the original "spirit of the Web"
What are Microformats NOT
- Open Ended Systems
- a new language
Using Microformats simply requires the use of XHTML tags. Microformats use XHTML tags such as cite, address, blockquote and cite, and attributes such as title, rel and rev, to create semantically appropriate blocks of code.
Adding this extra information to your code results in a wealth of machine-readable information for search engines  and other applications. This metadata can be used to establish relationships, draw connections, and improve the quality of search results.
The microformats.org open standards community has developed and popularized the hCard, hReview, and hCalendar open standards that enable any web-site to publish their contacts, events, and reviews respectively in a form both viewable by humans and understandable by machines..
Today, many blogging tools have adopted more semantic markup to indicate relationships - for example many blogs now support the use of XFN microformats.XFN enables web authors to indicate their relationship(s) to the people in their blogrolls or web-sites, simply by adding a 'rel' attribute to their <a href> tags, e.g.:
<a href="http://johnsblog.com/" rel="friend">John </a>
Explicit Vs Implicit metadata
In order to make your data more accessible for search engines, accurate and appropriate metadata is an important factor. Providing accurate explicit metadata for every web-page on your site may be an arduous task, (and one that often gets neglected).
With microformats, implicit metadata is provided by using the right markup . Athough this won’t alleviate the need for explicit metadata, it can act as a good addition (especially for dynamic pages where explicit meta information might not be as accurate as possible).
Several microformats have been developed to enable semantic markup of particular types of information.
- hCalendar - for events
- hCard - for contact information
- HReviewh(spec) - for reviews
- hResume - for resumes or CVs
- rel-directory(spec)- for distributed directory creation and inclusion
- rel-nofollow, an attempt to discourage 3rd party content spam (e.g.comment spam).
- rel-tag(spec) - for decentralized tagging.
- xFolk(spec) - for tagged links
- XFN - for social relationships
- XOXO - for lists and outlines
Use of microformats
Browser extensions, (e.g. Tails Export), provide the ability to detect microformats within HTML documents and export them into formats compatible with contact management and calendar software, such as Microsoft Outlook.
- Microformats.org - http://microformats.org/
- Microformats explained and their effect on Search Engine Optimization - http://blog.usweb.com/archives/how-microformats-affect-search-engine-optimization-seo/
- Microformats Primer - http://www.digital-web.com/articles/microformats_primer/
- Suda B (2006) Using Microformats. O' Reilly (Ebook) - http://www.oreilly.com/catalog/microformats