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.
The Accept request-header field can be used to specify certain media types which are acceptable for the response.
media-range = ( "*/*" | ( type "/" "*" ) | ( type "/" subtype ) ) *( ";" parameter ) accept-params = ";" "q" "=" qvalue *( accept-extension ) accept-extension = ";" token [ "=" ( token | quoted-string ) ] The asterisk "*" character is used to group media types into ranges, with "*/*" indicating all media types and "type/*" indicating all subtypes of that type.
The media-range MAY include media type parameters that are applicable to that range.
Each media-range MAY be followed by one or more accept-params, beginning with the "q" parameter for indicating a relative quality factor.
The first "q" parameter (if any) separates the media-range parameter(s) from the accept-params.
Quality factors allow the user or user agent to indicate the relative degree of preference for that media-range, using the qvalue scale from 0 to 1 (section 3.9). Note: Use of the "q" parameter name to separate media type parameters from Accept extension parameters is due to historical practice.