Possible Duplicate:
Save icon, is the floppy disk icon dead?
When designing UI, metaphors are important aspects, no doubt to that. But I often come across when picking the right metaphor is tricky as it seems that people tend to forget what the original item (on which metaphor is based) meant.
An example would be floppy drive metaphor, which is used as a "save" button. It was very relevant ten years ago as everyone knew that floppy is a media where you can save some files to. But new generation might not know what a floppy drive is, so do metaphors get out of date and need to be replaced or do they become symbols and will leave without relating them to real world objects?