FHIR (Fast Healthcare Interoperability Resources, an HL7 standard whose current normative release is R4/R4B, with R5 emerging) models clinical data as web-native resources — Patient, Appointment, Encounter, Observation, and many more — that are accessed over REST using JSON, the same patterns web developers already use everywhere else. That deliberate alignment with mainstream web technology is what makes FHIR dramatically more approachable than older healthcare formats for a software team without deep clinical-IT history.
US regulation turned FHIR from a promising standard into the mandated front door for health data. Certified EHRs are required to expose the USCDI (United States Core Data for Interoperability) data set through standardized FHIR APIs, which is precisely what makes patient-access apps and SMART-on-FHIR integrations feasible for startups rather than only for incumbents with custom interfaces. For a telemedicine product, this means a realistic path to reading a patient's medications, problems, and appointments through a documented API instead of negotiating a bespoke feed per hospital.
The important caveat, and the common pitfall, is that FHIR support is not uniform. Coverage varies by EHR vendor, by server, and by FHIR version, and a server may implement some resources richly and others not at all. The practical discipline is to scope every integration against the specific server's FHIR capability statement — the machine-readable declaration of exactly which resources, versions, and operations it supports — rather than against the vendor's marketing claim of "FHIR support." Teams that skip this routinely discover mid-build that a resource they assumed was available is read-only, partial, or absent.
