QPACK is a header field compression format for HTTP/3 that makes HTTP/2’s HPACK header compression format compatible with the QUIC protocol.

In HTTP/3, the way the sender’s encoder and the receiver’s decoder reach agreement on the the state of the dynamic table for compression would be very different compared to HTTP/2. In this post, I would like to talk some of understanding I gained while I was reading the RFC and implementing QPACK.