200 This code indicated a successful transmission. This is an information message, not an error.

302 - Moved Temporarily. Redirection to a new URL.
The original page has moved. This is not an error; most browsers invisibly retrieve the new page upon seeing this result.

304 - Not Modified. Display cached copy
If a browser already has a page in its cache, and that page is requested again, some browsers will ask the server send a request for the document to the web server along with a note telling the web server what the last-modified timestamp on the browsers cached copy is. If the copy on the server is not newer that the copy that the browser already has, the server will send back a 304 code, and the browser will display the cached copy. This is not an error.

400 - Bad Request ^*
The browser sent a request that the server could not understand.

401 - Unauthorized.
The user attempted to access a document but did not provide a valid username or password when requested by the server. (User Error)

403 - Forbidden ^*
The server does not have permission to display this document. The server administrator should check the permissions on the directory and/or file.

403.5 - 128 bit required
This error message indicates that the user is using a browser version that has 40 bit encryption. The server requires 128 bit encryption in order to permit access.

404 - Object Not found. ^*
(Page not found) This error code generally indicates that the user attempted to access a file that does not exist. The file has either been moved or deleted; the link to it was typed incorrectly on the web page; or the user entered the wrong URL.

412 - Precondition Failed ^*
The URL name could not be resolved.

500 - Server error. ^*
A server-related error occurred. Generally, this is due to a problem related to a CGI script. The file permissions must be set to allow it to be executed. Review your error logs for more information.

501 - Not Implemented ^*
The browser issued a request for a feature that has not been implemented on the server.

502 - Service Temporarily Overloaded
The server or gateway is either down or busy (has the maximum number of users it can handle)

503 - Service Unavailable ^*
The server is too busy or the gateway has timed out.