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Lesson 7 / 25

HTTP/2 and HTTP/3

Modern protocols that improve performance through multiplexing, header compression, and faster handshakes.

HTTP/2 multiplexing

HTTP/2 sends multiple requests over one connection simultaneously. No need to bundle assets or domain sharding. Header compression (HPACK) reduces overhead. Automatic prioritization of critical resources.

HTTP/3 and QUIC

HTTP/3 uses QUIC (UDP-based) instead of TCP. Faster connection establishment (0-RTT resumption), better loss recovery. Particularly beneficial for high-latency and mobile networks.

Protocol adoption timeline

HTTP/1.1 is legacy, HTTP/2 is supported by nearly all browsers, and HTTP/3 is growing but not universal. Check your server and CDN support. Most modern CDNs support both HTTP/2 and HTTP/3.

Quick check

Quick check: What is a key advantage of HTTP/3?

  • Smaller file sizes
  • No compression needed
  • It requires a separate connection per request
  • Uses UDP instead of TCP for faster handshake
Answer

Uses UDP instead of TCP for faster handshake — HTTP/3 runs over QUIC (UDP), which speeds up connection setup and recovers from loss better.