What is the difference between HTTP/2 and HTTP/3?

Answer

HTTP/2 introduced multiplexing of multiple requests over a single TCP connection, header compression, and server push, reducing latency compared with HTTP/1.1. However, because it runs over TCP, packet loss on one stream stalls all streams, a problem called head-of-line blocking. HTTP/3 solves this by running over QUIC, a transport built on UDP, where streams are independent so loss affects only the affected stream, and it integrates TLS 1.3 for faster connection setup. HTTP/3 also resumes connections more smoothly across network changes, benefiting mobile clients.