100 Continue 
101 Switching Protocols 
200 OK
201 Created 
202 Accepted 
203 Non-Authoritative Information 
204 No Content 
205 Reset Content 
206 Partial Content 
300 Multiple Choices 
301 Moved Permanently
302 Moved Temporarily 
303 See Other 
304 Not Modified 

(304 means the file was loaded from the browser cache instead of being resent by the server)

305 Use Proxy 
400 Bad Request 
401 Unauthorized 
402 Payment Required 
403 Forbidden 
404 Not Found 

405 Method Not Allowed 
406 Not Acceptable 
407 Proxy Authentication Required 
408 Request Time-Out 
409 Conflict 
410 Gone 
411 Length Required
412 Precondition Failed 
413 Request Entity Too Large 
414 Request-URL Too Large 
415 Unsupported Media Type 
500 Server Error 
501 Not Implemented 
502 Bad Gateway 
503 Out of Resources
504 Gateway Time-Out 
505 HTTP Version not supported