# QUIC Protocol
Confidence: high
Last verified: 2026-05-22
Generation: human_only


## TL;DR

QUIC is a UDP-based transport protocol developed by Google (2012) and standardized as IETF RFC 9000 (2021). It is the foundation of HTTP/3. Key innovations: 0-RTT connection, multiplexed streams without head-of-line blocking, built-in TLS 1.3 encryption, and connection migration (survives IP changes).

## Core Explanation

QUIC eliminates TCP's head-of-line blocking by treating each stream independently — lost packets in one stream don't block others. 0-RTT: for previously visited servers, data can be sent immediately. Connection ID enables seamless WiFi-to-cellular switching. QUIC is mandatory encrypted (TLS 1.3 built-in). Adoption: all Google services, Facebook, Cloudflare, ~35% of web traffic.

## Further Reading

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