Hypertext Transfer Protocol (HTTP/1.1): Semantics and Content
RFC 7231

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Internet Engineering Task Force (IETF)                  R. Fielding, Ed.
Request for Comments: 7231                                         Adobe
Obsoletes: 2616                                          J. Reschke, Ed.
Updates: 2817                                                 greenbytes
Category: Standards Track                                      June 2014
ISSN: 2070-1721

     Hypertext Transfer Protocol (HTTP/1.1): Semantics and Content

Abstract

   The Hypertext Transfer Protocol (HTTP) is a stateless application-
   level protocol for distributed, collaborative, hypertext information
   systems.  This document defines the semantics of HTTP/1.1 messages,
   as expressed by request methods, request header fields, response
   status codes, and response header fields, along with the payload of
   messages (metadata and body content) and mechanisms for content
   negotiation.

Status of This Memo

   This is an Internet Standards Track document.

   This document is a product of the Internet Engineering Task Force
   (IETF).  It represents the consensus of the IETF community.  It has
   received public review and has been approved for publication by the
   Internet Engineering Steering Group (IESG).  Further information on
   Internet Standards is available in Section 2 of RFC 5741.

   Information about the current status of this document, any errata,
   and how to provide feedback on it may be obtained at
   http://www.rfc-editor.org/info/rfc7231.

Fielding & Reschke           Standards Track                    [Page 1]
RFC 7231             HTTP/1.1 Semantics and Content            June 2014

Copyright Notice

   Copyright (c) 2014 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents
   (http://trustee.ietf.org/license-info) in effect on the date of
   publication of this document.  Please review these documents
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   include Simplified BSD License text as described in Section 4.e of
   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

   This document may contain material from IETF Documents or IETF
   Contributions published or made publicly available before November
   10, 2008.  The person(s) controlling the copyright in some of this
   material may not have granted the IETF Trust the right to allow
   modifications of such material outside the IETF Standards Process.
   Without obtaining an adequate license from the person(s) controlling
   the copyright in such materials, this document may not be modified
   outside the IETF Standards Process, and derivative works of it may
   not be created outside the IETF Standards Process, except to format
   it for publication as an RFC or to translate it into languages other
   than English.

Fielding & Reschke           Standards Track                    [Page 2]
RFC 7231             HTTP/1.1 Semantics and Content            June 2014

Table of Contents

   1. Introduction ....................................................6
      1.1. Conformance and Error Handling .............................6
      1.2. Syntax Notation ............................................6
   2. Resources .......................................................7
   3. Representations .................................................7
      3.1. Representation Metadata ....................................8
           3.1.1. Processing Representation Data ......................8
           3.1.2. Encoding for Compression or Integrity ..............11
           3.1.3. Audience Language ..................................13
           3.1.4. Identification .....................................14
      3.2. Representation Data .......................................17
      3.3. Payload Semantics .........................................17
      3.4. Content Negotiation .......................................18
           3.4.1. Proactive Negotiation ..............................19
           3.4.2. Reactive Negotiation ...............................20
   4. Request Methods ................................................21
      4.1. Overview ..................................................21
      4.2. Common Method Properties ..................................22
           4.2.1. Safe Methods .......................................22
           4.2.2. Idempotent Methods .................................23
           4.2.3. Cacheable Methods ..................................24
      4.3. Method Definitions ........................................24
           4.3.1. GET ................................................24
           4.3.2. HEAD ...............................................25