As mentioned in Rogers book, “metaphors are considered to be a central component of a conceptual model”. Imagine you are making a software and you want to make it easy to use so that users easily understand how it works. One way is to tell them how it works, but another way is to make a metaphor so that they can remember it and they predict how it works. So what you want is to match the user’s mental model to the model of the software, which sometimes it does match and sometime it does not. For instance, one of the oldest metaphors is the desktop metaphor which was first introduced by Alan Kay at Xerox PARC in 1970. Or as one of the failures, Microsoft Bob introduced in 1995 by Microsoft could be a good example. As seen in the picture, it looks like a living room which has a calendar, desk and etc.
Another concept that I would like to talk about is “Skeuomorphism” which is “a derivative object that retains ornamental design cues from structures that were necessary in the original”. For example, in the following picture which is a digital audio program, you do not actually need nubs, but they put nubs on it as a metaphor as a Skeuomorphism to sort of a cue to you that it works the same way as a real nub.
Or this one is an electric kettle but they make it as a same shape as a kettle for the stove.