Any operation should be able to be undone/redone to any desired levels of precision and depth!

Everyone who ever used a text editor with undo/redo functionality would surely never want to go backward and renounce to this comfort. We all make errors and it is so comfortable to know that any error can be undone. Fortunately, software is one of the rare technologies that enables us to create undo/redo functionality. Think for example of a surgeon. He can't undo a bad cut. He just has to get it right the first time.

Unfortunately, integrating undo/redo functionality in software can be a rather complicated task, but we should be aware that more and more users consider it as a state of the art feature. Undo/redo functionality can be determinant for a product's success.