Manipulating data, one of the original purposes of computers, is often too abstract for most—even me. It helps to make things visible. Graphical user interfaces unpack some of the complexity in computing, and their implementation became a key to unlocking computers for most people in the ’80s and ’90s. The interfaces we build are where we put the padding. You give a user something to grasp onto when you make a metaphor solid. In the case of software on a screen, the metaphors visually explain the functions of an interface, and provide a bridge from a familiar place to a less known area by suggesting a tool’s function and its relationship to others.

For instance, if I say «This is a Trash Bin,» you may not know a computer’s file management system or directory structures, but you’ve got a pretty good idea of how trash bins work, so you can deduce that the unwanted files go in the trash bin, and you’ll be able to retrieve them until the bin is emptied.

Metaphors are assistive devices for understanding.

Frank Chimero.