How does QUIC improve upon TCP for modern web applications?

QUIC (HTTP/3 transport) runs over UDP, providing: 1) No head-of-line blocking (independent streams), 2) 0-RTT connection resumption (faster reconnects), 3) Connection migration (survives IP changes - mobile), 4) Built-in encryption (TLS 1.3 integrated), 5) Improved congestion control (in userspace, updatable). Eliminates TCP issues: handshake overhead, HoL blocking, OS-level rigidity. Deployed by Google, Cloudflare. Trade-offs: UDP blocking by some networks, higher CPU usage, middlebox interference.