In computer programming, error coes are enumerated messages that correspond to faults in a specific software application. They are typically used to identify faulty hardware, software, or incorrect user input in programming languages that lack exception handling, although they are sometimes also be used in conjunction with exception handling. Error codes are not to be confused with return codes, although both are commonly used together in error handling. Some of the most severe error codes visible to users are the "Blue Screen of Death" codes provided by the Microsoft Windows operating systems.