To deliver information to providers across the U.S., the Agency for Healthcare Research and Quality's National Resource Center for Health IT (NRC) created a public domain Web site containing a number of tools and resources. Specifically lacking from this Web site is a glossary of health IT terminology. To address this omission and respond to requests from Web site users,the Regenstrief Institute created the Health IT Glossary. This glossary is designed to provide novices, providers and others new to health IT, with a single source to find basic definitions for a broad range of terms, consistent with the Office of the National Coordinator (ONC) effort. The glossary is a living document, and feedback is welcomed from the health informatics community.