# Comparison with HTTP/2 HTTP/3 is designed for QUIC, which is a transport protocol that handles streams by itself. HTTP/2 is designed for TCP, and therefore handles streams in the HTTP layer. ## Similarities The two protocols offer clients virtually identical feature sets. * Both protocols offer server push support * Both protocols have header compression, and QPACK and HPACK are similar in design. * Both protocols offer multiplexing over a single connection using streams ## Differences The differences are in the details and primarily there thanks to HTTP/3's use of QUIC: * HTTP/3 has better and more likely to work early data support thanks to QUIC's 0-RTT handshakes, while TCP Fast Open and TLS usually sends less data and often faces problems. * HTTP/3 has much faster handshakes thanks to QUIC vs TCP + TLS. * HTTP/3 does not exist in an insecure or unencrypted version. HTTP/2 can be implemented and used without HTTPS - even if this is rare on the Internet. * HTTP/2 can be negotiated directly in a TLS handshake with the ALPN extension, while HTTP/3 is over QUIC so it needs an `Alt-Svc:` header response first to inform the client about this fact. * The base HTTP/3 specification doesn't define prioritization itself. The HTTP/2 approach to prioritization has been deemed too complicated and is deprecated by the latest revision of the HTTP/2 specification [RFC 9113](https://www.rfc-editor.org/rfc/rfc9113.html). A simpler alternative, the Extensible Prioritization Scheme for HTTP ([RFC 9218](https://www.rfc-editor.org/rfc/rfc9218.html)), has been published separately, which can be used in both HTTP/2 and HTTP/3. --- # 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-h2.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.