Why does HTTP/3 use UDP?
QUIC runs over UDP so it can implement its own reliable, encrypted, multiplexed streams in user space instead of waiting on operating-system TCP changes. UDP is just the delivery vehicle. QUIC adds reliability, congestion control and TLS 1.3 on top, and supports faster connection setup and connection migration.
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HTTP/1.1, HTTP/2 and HTTP/3: What Each Version Fixed and What It Left BrokenPersistent connections, multiplexing, header compression and QUIC: each HTTP version removed one bottleneck and exposed the next. How to choose and verify.
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