Comment by blueflow

To understand icons, they must resemble something you have seen before. If you were born in 2005, you won't know what the button with the floppy disk on it does because you have never seen or used a floppy.

Or a cloud to mean "upload", or a thin moon crescent to mean "sleep".

These are things that don't derive from the real world (any more) and must be explicitly communicated.