§ 01
Definition
Google first developed QUIC, and the IETF standardised it in 2021 as RFC 9000. It was designed to set up encrypted connections faster than TCP plus TLS and to handle packet loss and network changes better.
§ 02
How it works
QUIC combines the transport and encryption handshakes, so a connection can start in one round trip, or zero for a returning visitor. Each stream is independent, so one lost packet does not stall the others. Connection IDs let a session survive a switch from Wi-Fi to mobile data.
§ 03
Why it matters
QUIC matters to VPN users in two ways. Some VPN and proxy tools now tunnel over QUIC (for example via MASQUE) to look like ordinary HTTP/3 traffic. And some corporate firewalls block QUIC, which can make browsing behave oddly until the browser falls back to TCP.