Technorati is an online index that gathers together blog entries and news articles on common topics using the folksonomy created by the authors. Technorati aggregates these tags and uses them to enhance their blog/news search service.
Many bloggers will hand-code tags that link to Technorati in their articles, or implement plugins that use the Technorati API to generate the links. Technorati can also identify tags by using the
rel="tag" descriptor in links.