Reuters announced the release of an open Application Programming Interface (API) for its new Calais web service. The API, which provides commercial and non-commercial parties with free access to semantic tagging capabilities to enhance their applications and content, is available at OpenCalais.com. The Calais web service enables publishers, bloggers, and sites of all kinds to automatically metatag the people, places, facts, and events in their content to increase its search relevance and accessibility on the web. It also lets content consumers, such as search engines, news portals, bookmarking services, and RSS readers, submit content for automatic semantic metatagging. Calais is a new Reuters initiative that supports the interoperability of content and the development of the semantic web.