If you’re lucky, nothing. If you’re a typical commercial website owner, however, a lot. Your website could be attacked maliciously and control assumed by an unknown third party. That third party could take your website down and surreptitiously add malicious code, or try to gain sensitive information about you, your business, or your customers. You also don’t want a slow website or, worse, a timed out connection due to the server being overloaded with too many websites and traffic!