HTTP Headers
HTTP headers are used to transfer all sorts of information between client and server. There are four categories of headers:
- General
Information not related to the client, server, or HTTP
- Request
Preferred document formats and server parameters
- Response
Information about the server sending the response
- Entity
Information on the data being sent between the client and server
General headers and entity headers are the same for both the server and client.
All headers in HTTP messages contain the header name followed by a
colon (:), then a space, and the value of the header. Header names
are case-insensitive (thus, Content-Type
is the
same as Content-type
). The value of a header can
extend over multiple lines by preceding each extra line with at least
one space or tab character.
General Headers
General headers are used in both client requests and server responses. Some may be more specific to either a client or server message.
Client Request Headers
Client header data communicates the client’s configuration and preferred document formats to the server. Request headers are used in a client message to provide information about the client.
Server Response Headers
The response headers described here are used in server responses to communicate information about the server and how it may handle requests.
Entity Headers
Entity headers are used in both client requests and server responses. They supply information about the entity body in an HTTP message.
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