An HTTP server returns an HTTP response to the HTTP client that made the HTTP request. The response either confirms that the requested action was performed or returns information requested by the client.

An HTTP response consists of a status line, a set of message headers, and, possibly a message body. The status line contains a status code and a phrase indicating the high level response to the request. Codes and phrases are defined by the HTTP standard specification The most common code and phrase is 200 OK, which mean that the request was processed successfully. Other possible values report different kinds of errors.

The message headers in an HTTP response describe the characteristics of the message body. HTTP response message headers are structured as name/value pairs and are defined by the HTTP standard specification.

The message body in an HTTP response, if one is present, provides the data requested by the HTTP client.