HTTP/1
- came in 1996
- built on top of TCP
- every request to same server requires a separate TCP connection
HTTP/1.1
- came in 1997
- introduced
keep-alive mechanism (prevents unnecessary 3-way handshake for each request between same client and server)
- added http pipelining
- TLS/SSL is optional
HTTP/2
- came in 2015
- introduced http streams
- introduced push capability (allow updates to be sent to client)
- TLS 1.2+
HTTP/3
- came in June 2022
- uses new protocol:
QUIC instead of TCP
QUIC is based on UDP- introduces stream as the first class citizen in transport layer
QUIC uses concept of connection ID which helps in switching networks
- It solves the issue of having to switch multiple connections (3G to Wifi to any other network) which is very sluggish
- TLS 1.3