When your old DOS-based computers underwent the change from black & white to color displays, many new commands had to be created for the user to change these new properties. Then, when Windows was introduced, the developer knew that there would be many activities that would be performed over and over by the user. The outcome of this knowledge led to the creation of a 'set' of Windows dialogs that interfaced with the user. As more and more programs were written for Windows, the dialogs in this set were copied by many programmers. It was around this time that developers started calling them the Common Dialogs.