The Status-Code element is a 3-digit integer result code of the attempt to understand and satisfy the request. The Status-Code is intended for use by automata.
The first digit of the Status-Code defines the class of response. The last two digits do not have any categorization role. There are 5 values for the first digit:
1xx - Information Provisional information on the progress of the request 2xx -  Success The action was successfully received, understood, and accepted 3xx - Redirection Further action must be taken in order to complete the request 4xx - Client Error The request contains bad syntax or cannot be fulfilled 5xx - Server Error     The server failed to fulfill an apparently valid request