HTTP Status Codes
This is a breakdown of the top level of status codes, you can click through (or use the similar links in the menu) to view a full breakdown of the codes and their uses in each section.
This class of status code indicates a provisional response, that is an interim status update for information purposes only. For example a status code of 100 indicates that he client can continue with the request and that no errors have been detected.
This class of status code indicates that the client's request was successfully received, understood, and accepted.
This class of status code indicates that further action needs to be taken by the user agent in order to fulfill the request.
The 4xx class of status code is intended for cases in which the client seems to have made an error. For example requesting a page that does not exist - this example is indicated with a 404 error.
Response status codes beginning with the digit "5" indicate cases in which the server is aware that it has made an error or is incapable of performing the request. For example if the server is overloaded (503 Service Unavailable would be an appropriate status to issue).