HTTP/2
A major HTTP upgrade that multiplexes many requests over one connection to cut latency.
HTTP/2 is the second major version of HTTP, designed to fix HTTP/1.1’s one-request-per-connection bottleneck. It multiplexes many concurrent request and response streams over a single TCP connection, compresses headers (HPACK), and lets the server push resources proactively — all binary-framed rather than plain text.
Worked example: a page that needs 50 assets loads them over one HTTP/2 connection with interleaved streams, instead of opening six parallel HTTP/1.1 connections and queueing the rest. Gotcha: multiplexing removes application-level head-of-line blocking but not TCP-level — because all streams share one TCP connection, a single lost packet stalls every stream until it is retransmitted, the exact limitation HTTP/3 escapes by moving to UDP-based QUIC.