Definitions    
Term Definition Source
Query-based exchange Query-based exchange is used by providers to search and discover accessible clinical sources on a patient. This type of exchange is often used when delivering unplanned care. https://www.healthit.gov/providers-professionals/health-information-exchange/what-hie
Directed exchange Directed exchange is used by providers to easily and securely send patient information—such as laboratory orders and results, patient referrals, or discharge summaries—directly to another health care professional. This information is sent over the internet in an encrypted, secure, and reliable way amongst health care professionals who already know and trust each other, and is commonly compared to sending a secured email. This form of information exchange enables coordinated care, benefitting both providers and patients. https://www.healthit.gov/providers-professionals/health-information-exchange/what-hie
Consumer-mediated exchange Consumer-mediated exchange provides patients with access to their health information, allowing them to manage their health care online in a similar fashion to how they might manage their finances through online banking. https://www.healthit.gov/providers-professionals/health-information-exchange/what-hie
Federated Model Organization control of healthcare record and provides the framework for data-sharing capability to enterprises; Also known as a decentralized or distributed model http://www.himss.org/sites/hde/files/d7/HIMSSorg/Content/files/HIE/HIE_GuideWhitePaper.pdf
Centralized Model Patient health data is collected from local sources, but stored in a central respository. If an entity requests data, the transaction is routed through the central respository; Also known as a consolidated model http://www.himss.org/sites/hde/files/d7/HIMSSorg/Content/files/HIE/HIE_GuideWhitePaper.pdf
Hybrid Model A cross between centralized and decentralized architecture. This model provides the interface engine for which organizational entities communciate. http://www.himss.org/sites/hde/files/d7/HIMSSorg/Content/files/HIE/HIE_GuideWhitePaper.pdf
Certificate Authority A trusted entity that issues and revokes public key certificates. https://www.healthit.gov/sites/default/files/trustframeworkfinal.pdf
Registration Authority Act as an intermediary between users and certificate authorities, reviewing and approving certificate requests. https://www.healthit.gov/sites/default/files/trustframeworkfinal.pdf