Health Level Seven (HL7) is one of several ANSI-accredited Standards Developing Organizations (SDOs) operating in the Health Care arena. Like all ANSI-accredited SDOs, Health Level Seven adheres to a strict and well-defined set of operating procedures that ensures consensus, openness and balance of interest. Headquartered in Ann Arbor, MI, Health Level Seven is like most of the other SDOs in that it is a not-for-profit volunteer organization.

Health Level Seven (HL7) is an application protocol for electronic data exchange of information in Health Care environments. HL7 is a collection of standard formats used by vendors of hospital information systems, clinical laboratory systems, enterprise systems, and pharmacy systems. HL7 standardizes the protocols and structure for exchanging key sets of health data at the application level, which is the seventh level of the ISO open systems model.

Level Seven refers to the application level, the highest level of the Open System Interconnection (OSI) model of the International Organization for Standardization (ISO). The OSI model is a networking architecture for moving data from one software application to another application located on another computer. This model divides the process of moving that data into seven steps or layers. From lowest to highest, the layers are: physical, link, network, transport, session, presentation, and application. The lowest two layers, physical and link, are handled by hardware. The upper five layers are handled by software. The issues that are addressed or that occur at the seventh level include the data to be exchanged, the timing of the exchanges, and the communication of certain application-specific errors between applications. HL7 is a framework an accepted set of protocols that defines these three elements.