First, you need to know what error codes are. In a programming language, an error code is a numeric or alphanumeric code displayed on the screen. The type of error determines the error code displayed on the screen, typically consisting of 3 to four digits, followed by a brief message describing the error. After an error code has been displayed on the screen, various errors can be found and eliminated during the testing phase of software and hardware. You or a technician can troubleshoot the problem and resolve the issue by using the code.