Epic: #15
Block: 6 — HTTP
Series order: 11 of 18
Description
Why Google moved HTTP off TCP entirely, what QUIC provides that TCP couldn't, and how HTTP/3 changes the connection model at a fundamental level.
Key topics
- TCP-level HOL blocking: one lost packet stalls all streams, even unrelated ones
- Why you can't fix this inside TCP — it's baked into the protocol's ordering guarantee
- QUIC: a new transport protocol built on top of UDP, developed by Google, standardised by IETF
- Connection IDs: connections survive IP address changes (e.g. switching from WiFi to mobile)
- Independent streams: a lost packet only blocks the stream it belongs to
- 0-RTT connection establishment: combining the transport and TLS handshake
- HTTP/3: HTTP semantics mapped onto QUIC streams instead of TCP
- QUIC adoption: where it is today, how to check if a site uses it (DevTools Network panel)
Epic: #15
Block: 6 — HTTP
Series order: 11 of 18
Description
Why Google moved HTTP off TCP entirely, what QUIC provides that TCP couldn't, and how HTTP/3 changes the connection model at a fundamental level.
Key topics