International standardHypertext Transfer Protocol Version 3 (HTTP/3) (draft)
Developed byIETF
IntroducedInternet-Draft as of July 2020

HTTP/3 is the upcoming third major version of the Hypertext Transfer Protocol used to exchange information on the World Wide Web, succeeding HTTP/2.[1][2]

HTTP/3 uses the same semantics as HTTP/1.1 and HTTP/2 (the same operations like GET and POST) and same response codes (like 200 or 404) but uses a different transport protocol aware of these semantics and capable of recovering from packet loss with minimal performance loss. HTTP/3 is developed to fix the major problem of HTTP/2 called "head-of-line blocking" that arises from reliance on TCP: because the parallel nature of HTTP/2's multiplexing is not visible to TCP's loss recovery mechanisms, a lost or reordered packet causes all active transactions to experience a stall regardless of whether that transaction was impacted by the lost packet.

As of July 2020, HTTP/3 protocol is an Internet-Draft and has multiple implementations, and according to W3Techs 6.3% of the top 10 million websites support HTTP/3.[3] Stable versions of Firefox and Chrome support HTTP/3 in its current form, but have it disabled by default. Safari 14 will ship with HTTP/3 enabled by default.

  1. ^ Bishop, M. (2 July 2020). "Hypertext Transfer Protocol Version 3 (HTTP/3)". Retrieved 1 July 2020.
  2. ^ Bishop, Mike (21 February 2020). Hypertext Transfer Protocol Version 3 (HTTP/3). IETF. I-D draft-ietf-quic-http-27.
  3. ^ "Usage of HTTP/3 for websites". World Wide Web Technology Surveys. W3Techs. Retrieved 3 July 2020.

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