FHIR stands for Fast Healthcare Interoperability Resources. It is a standard for exchanging healthcare information electronically and combines the best features from HL7 v2, HL7 v3, and CDA, while also adding several significant improvements over previous standards.
Unlike HL7 standards, which were not freely available until 2013, the specifications for FHIR are 100% available without a login or any restrictions.
FHIR employs many popular, modern web technologies that developers are already familiar with such as HTTPS, REST, XML, JSON, ATOM, and OAuth.