What are the most common HTTP Error Codes?

The following table lists the most common HTTP error codes:

Error Code Description
200 Successful transmission.
302 Redirection to a new URL.
304 Use local copy. The requested document will be retrieved from the client's cache.
401 Unauthorized. The user asked for a document and did not provide a username or password.
403 Forbidden. Access is explicitly denied.
404 Not found. This message can also be used to deny access to a resource or to imply to a user that
the resource does not exist.
500 Server error. A server-related error has occurred and the system administrator should check the error log.
8181 Certificate has expired (this applies to secure servers only).