HL7 (Health Level Seven) is both the standards organization behind most healthcare data exchange and, colloquially, the name of its long-running v2 messaging standard that still powers the interface engines inside hospitals today. When a hospital integration team says they will "send you an HL7 feed," they usually mean HL7 v2 messages — terse, pipe-delimited event notifications fired whenever something happens, such as a patient being admitted, a result being finalized, or an appointment being scheduled.
The HL7 family actually spans three generations that solve the same interoperability problem with very different ergonomics: HL7 v2 (real-time event feeds), CDA and C-CDA (structured clinical documents, such as a discharge summary), and FHIR (modern web APIs using REST and JSON). Each generation reflects the technology of its era, and crucially, all three remain in active use simultaneously, because hospitals rarely retire working interfaces.
For a telemedicine product, integration planning largely comes down to choosing which HL7 generation each individual data flow will ride on, and that choice is dictated by what the specific health system actually exposes rather than by your preference. You might pull patient demographics and appointments through FHIR while receiving result notifications over an HL7 v2 feed from the same hospital. The common pitfall is assuming a modern FHIR API will be available for everything; in many real deployments the only practical path for a given data type is still a v2 interface maintained by the hospital's integration team.
