A message box is a secondary window that displays a message; information about a particular situation or condition. Messages are an important part of the interface for any software product. Messages that are too generic or poorly written frustrate users, increase support costs, and ultimately reflect on the quality of the product. Therefore, it is worthwhile to design effective message boxes.
However, it is even better to avoid creating situations that require you to display a message. For example, if there may be insufficient disk space to perform an operation, rather than assuming that you will display a message box, check before the user attempts the operation and disable the command.