Types of HTTP Error and Status Codes
Included in the HTTP server response data for each request is a code number indicating the result of the request. These result codes are three-digit numbers divided into categories as follows:
100-199 : informational status
200-299 : success status
300-399 : redirection status
400-499 : client errors
500-599 : server errors
Ref: compnetworking.about.com
