14 Header Field Definitions

This section defines the syntax and semantics of all standard HTTP/1.1 header fields. For entity-header fields, both sender and recipient refer to either the client or the server, depending on who sends and who receives the entity.

• 14.1 Accept
• 14.2 Accept-Charset
• 14.3 Accept-Encoding
• 14.4 Accept-Language
• 14.5 Accept-Ranges
• 14.6 Age
• 14.7 Allow
• 14.8 Authorization
• 14.9 Cache-Control
  • 14.9.1 What is Cachable
  • 14.9.2 What May be Stored by Caches
  • 14.9.3 Modifications of the Basic Expiration Mechanism
  • 14.9.4 Cache Revalidation and Reload Controls
  • 14.9.5 No-Transform Directive
  • 14.9.6 Cache Control Extensions
• 14.10 Connection
• 14.11 Content-Base
• 14.12 Content-Encoding
• 14.13 Content-Language
• 14.14 Content-Length
• 14.15 Content-Location
• 14.16 Content-MD5
• 14.17 Content-Range
• 14.18 Content-Type
• 14.19 Date
• 14.20 ETag
• 14.21 Expires
• 14.22 From
• 14.23 Host
• 14.24 If-Modified-Since
• 14.25 If-Match
• 14.26 If-None-Match
• 14.27 If-Range
• 14.28 If-Unmodified-Since
• 14.29 Last-Modified
• 14.30 Location
• 14.31 Max-Forwards
• 14.32 Pragma
• 14.33 Proxy-Authenticate
• 14.34 Proxy-Authorization
• 14.35 Public
• 14.36 Range
  • 14.36.1 Byte Ranges
  • 14.36.2 Range Retrieval Requests
• 14.37 Referer
• 14.38 Retry-After
• 14.39 Server
• 14.40 Transfer-Encoding
• 14.41 Upgrade
• 14.42 User-Agent
• 14.43 Vary
• 14.44 Via
• 14.45 Warning
• 14.46 WWW-Authenticate