# QUIC streams and HTTP/3 HTTP/3 is made for QUIC so it takes full advantage of QUIC's streams, where HTTP/2 had to design its entire stream and multiplexing concept of its own on top of TCP. HTTP requests done over HTTP/3 use a specific set of streams. ## HTTP/3 frames HTTP/3 means setting up QUIC streams and sending over a set of frames to the other end. There's but a small fixed number (actually nine on December 18th, 2018!) of known frames in HTTP/3. The most important ones are probably: * HEADERS, that sends compressed HTTP headers * DATA, sends binary data contents * GOAWAY, please shutdown this connection ## HTTP Request The client sends its HTTP request on a client-initiated *bidirectional* QUIC stream. A request consists of a single HEADERS frame and might optionally be followed by one or two other frames: a series of DATA frames and possibly a final HEADERS frame for trailers. After sending a request, a client closes the stream for sending. ## HTTP Response The server sends back its HTTP response on the bidirectional stream. A HEADERS frame, a series of DATA frames and possibly a trailing HEADERS frame. ## QPACK headers The HEADERS frames contain HTTP headers compressed using the QPACK algorithm. QPACK is similar in style to the HTTP/2 compression called HPACK ([RFC 7541](https://httpwg.org/specs/rfc7541.html)), but modified to work with streams delivered out of order. QPACK itself uses two additional unidirectional QUIC streams between the two end-points. They are used to carry dynamic table information in either direction. --- # Agent Instructions: Querying This Documentation If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question. Perform an HTTP GET request on the current page URL with the `ask` query parameter: ``` GET https://http3-explained.haxx.se/en/h3/h3-streams.md?ask= ``` The question should be specific, self-contained, and written in natural language. The response will contain a direct answer to the question and relevant excerpts and sources from the documentation. Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.