The client and the server can pass some additional information using
HTTP headers through a request or a response.
HTTP header is basically a key-value, where its key is a case-insensitive string and value is a single or array of string.
These are grouped into different categories below, based on their context:
General headers: this is used for both request and response and there is no relation to the message data.
Request headers: these are client headers, sent during the
HTTPrequest and they contain information about the resource to be fetched.
Response headers: these are server headers and are part of the
HTTPresponse. They give more details about the server resource context.
Entity headers: these headers give meta-information about the content of the body of the message like
To learn more about various
HTTP headers options, please go here.