WebRTC
The browser standard for real-time audio, video and data — the engine inside nearly every telemedicine consultation.
In one line
WebRTC lets two browsers (or apps) exchange encrypted audio, video and data directly, peer-to-peer, with no plugins — which is why a video consult can run in a plain browser tab.
How it works
Three pieces. Signaling (not standardised — usually your own WebSocket server) exchanges session descriptions so peers agree on codecs and addresses. ICE/STUN/TURN punch through NATs and firewalls: STUN discovers public addresses, TURN relays media when a direct path is impossible (the part that costs money at scale). Then encrypted media (SRTP) and a data channel flow peer-to-peer. Group calls add an SFU server that forwards streams instead of full peer-meshes.
Where it shows up in digital health
Every browser-based teleconsultation (including eSanjeevani-class national platforms), tele-ICU camera feeds, remote proctoring of procedures, and the data channel for live device readings during a video visit. Platform-side, the build decision is usually "raw WebRTC + your own SFU" vs. managed media platforms — a cost/control trade-off.