Comment by vivzkestrel

QUIC is actually a level 4 protocol, on the same level as UDP and TCP, it could work on IP directly, making it QUIC/IP.

They chose to keep the UDP layer because of its minimal overhead over raw IP and for better adoption and anti-ossification reasons, but conceptually, forget about UDP, QUIC is a TCP replacement that happens to be built on top of UDP.

Now for the answers:

- Why not HTTP over UDP? UDP is an unreliable protocol unsuitable for HTTP. HTTP by itself cannot deal with packet loss, among other things.

- Why not keep HTTP/2? HTTP/2 is designed to work with TCP and work around some of its limitations, it could probably work over QUIC too, but you would lose most of the advantages of QUIC

- Why not got back to HTTP/1? I could turn out to be a better choice than HTTP/2, but it is not a drop-in replacement either, and you would lose all the intersting features introduced since HTTP/2

That's basically what QUIC is? It is a UDP based protocol over which HTTP can be run.

How else would you consider "just" switching HTTP to UDP? There are minimum required features such as 1. congestion control 2. multiplexed streams 3. encryption and probably a few others that I forgot about.