Quando un browser richiede ad un web server di visualizzare una pagina web, puņ occorrere un errore, prontamente riportato dal vostro browser; un esempio č il noto Errore 404 che gestisce "Il file non trovato". Di seguito č riportata una lista di tali errori:
| Messaggio | Descrizione |
| 100 Continue | Only a part of the request has been received by the server, but as long as it has not been rejected, the client should continue with the request |
| 101 Switching Protocols | The server switches protocol |
| Messaggio | Descrizione |
| 200 OK | The request is OK |
| 201 Created | The request is complete, and a new resource is created |
| 202 Accepted | The request is accepted for processing, but the processing is not complete |
| 203 Non-authoritative Information | |
| 204 No Content | |
| 205 Reset Content | |
| 206 Partial Content |
| Messaggio | Descrizione |
| 300 Multiple Choices | A link list. The user can select a link and go to that location. Maximum five addresses |
| 301 Moved Permanently | The requested page has moved to a new url |
| 302 Found | The requested page has moved temporarily to a new url |
| 303 See Other | The requested page can be found under a different url |
| 304 Not Modified | |
| 305 Use Proxy | |
| 306 Unused | This code was used in a previous version. It is no longer used, but the code is reserved |
| 307 Temporary Redirect | The requested page has moved temporarily to a new url |
| Messaggio | Descrizione |
| 400 Bad Request | The server did not understand the request |
| 401 Unauthorized | The requested page needs a username and a password |
| 402 Payment Required | You can not use this code yet |
| 403 Forbidden | Access is forbidden to the requested page |
| 404 Not Found | The server can not find the requested page |
| 305 Use Proxy | |
| 405 Method Not Allowed | The method specified in the request is not allowed |
| 406 Not Acceptable | The server can only generate a response that is not accepted by the client |
| 407 Proxy Authentication Required | You must authenticate with a proxy server before this request can be served |
| 408 Request Timeout | The request took longer than the server was prepared to wait |
| 409 Conflict | The request could not be completed because of a conflict |
| 410 Gone | The requested page is no longer available |
| 411 Length Required | The "Content-Length" is not defined. The server will not accept the request without it |
| 412 Precondition Failed | The precondition given in the request evaluated to false by the server |
| 413 Request Entity Too Large | The server will not accept the request, because the request entity is too large |
| 414 Request-url Too Long | The server will not accept the request, because the url is too long. Occurs when you convert a "post" request to a "get" request with a long query information |
| 415 Unsupported Media Type | The server will not accept the request, because the media type is not supported |
| 417 Expectation Failed |
| Messaggio | Descrizione |
| 500 Internal Server Error | The request was not completed. The server met an unexpected condition |
| 501 Not Implemented | The request was not completed. The server did not support the functionality required |
| 502 Bad Gateway | The request was not completed. The server received an invalid response from the upstream server |
| 503 Service Unavailable | The request was not completed. The server is temporarily overloading or down |
| 504 Gateway Timeout | The gateway has timed out |
| 505 HTTP Version Not Supported | The server does not support the "http protocol" version |