STUN (Session Traversal Utilities for NAT) and TURN (Traversal Using Relays around NAT) are complementary protocols used to establish peer-to-peer connectivity across Network Address Translators and firewalls. STUN allows a client to discover its public IP address and port mapping, while TURN provides a relay server as a fallback when direct connectivity cannot be achieved. Together they form the ICE (Interactive Connectivity Establishment) framework used by WebRTC.