QUIC, standardised in RFC 9000 (May 2021), was designed by Google and IETF to replace TCP + TLS as the transport for the modern web. It runs on UDP — making it deployable without kernel changes — and folds TLS 1.3, multiplexing, and reliable ordered streams into a single protocol. Crucially, each QUIC stream gets its own loss recovery, so a dropped packet on one stream does not block delivery on the others. This solves HTTP/2's worst pathology over flaky networks.
For streaming the relevant QUIC features are: 0-RTT connection resumption (faster startup when a client reconnects), unreliable datagrams (RFC 9221), independent stream loss recovery, and clean integration with TLS 1.3 fingerprinting. HTTP/3 (RFC 9114, June 2022) runs HTTP semantics on QUIC and is now the default for many large CDNs. Beyond HTTP, WebTransport and Media over QUIC expose QUIC's primitives directly to streaming applications, opening designs that neither HTTP nor WebRTC could express.
QUIC's operational story is mixed. Browsers support it everywhere, and major CDNs (Cloudflare, Fastly, Akamai, Google) serve QUIC by default for HTTPS traffic. But middleboxes — corporate proxies, security gateways, some enterprise firewalls — sometimes block UDP/443 entirely or fall back to TCP. Encryption hides what used to be observable, so on-path traffic shaping no longer works the same way, which has been a point of friction with some ISPs.
