# HTTP/3 over QUIC

The HTTP layer, called HTTP/3, does HTTP-style transports, including HTTP header compression using QPACK - which is similar to the HTTP/2 compression named HPACK.

The HPACK algorithm depends on an *ordered* delivery of streams so it was not possible to reuse it for HTTP/3 without modifications since QUIC offers streams that can be delivered out of order. QPACK can be seen as the QUIC-adapted version of [HPACK](https://httpwg.org/specs/rfc7541.html).


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