HTTP/3 (QUIC)
HTTP/3 is the latest version of the HTTP protocol for transferring web content. It is based on QUIC, a transport protocol originally developed by Google and now established as an open internet standard (IETF), which shortens connection setup and copes with packet loss better than the previous HTTP/2 – particularly valuable on mobile or unstable connections.
In practice
Enabling HTTP/3 is usually a matter of hosting or server configuration rather than a change to your own website code. It is worth asking your hosting provider whether HTTP/3 is already supported.