The Status-Code element in a server response is a 3-digit integer where the first digit of the Status-Code defines the class of response and the last two digits do not have any categorization role. There are 5 values for the first digit:
There are 5 different types of Status Codes.
1xx Informational - This class of status code indicates a provisional response, consisting only of the Status-Line and optional headers, and is terminated by an empty line. There are no required headers for this class of status code.
2xx Success - This class of status code indicates that the client’s request was successfully received, understood, and accepted.
3xx Redirection - This class of status code indicates that further action needs to be taken by the user agent in order to fulfill the request. The action required MAY be carried out by the user agent without interaction with the user if and only if the method used in the second request is GET or HEAD
4xx Client Error -
The 4xx class of status code is intended for cases in which the client seems to have erred. Except when responding to a HEAD request, the server SHOULD include an entity containing an explanation of the error situation, and whether it is a temporary or permanent condition
5xx Server Error -
Response status codes beginning with the digit “5” indicate cases in which the server is aware that it has erred or is incapable of performing the request