HTTP HTTP Status Codes
Introduction
In HTTP, status codes are a machine-readable mechanism indicating the result of a previously issued request. From RFC 7231, sec. 6: "The status-code element is a three-digit integer code giving the result of the attempt to understand and satisfy the request."
The formal grammar allows codes to be anything between 000 and 999. However, only the range from 100 to 599 has assigned meaning.
Remarks
HTTP/1.1 defines a number of numeric HTTP status codes that appear in the status line - the first line of an HTTP response - to summarise what the client should do with the response.
The first digit of a status codes defines the response’s class:
1xxInformational2xxClient request successful3xxRequest redirected - further action necessary, such as a new request4xxClient error - do not repeat the same request5xxServer error - maybe try again
In practice, it is not always easy to choose the most appropriate status code.
