Stories say that when the Macintosh was complete, there was a big party at Steve Jobs' place. He made the team that worked on the machine sign a piece of paper. The piece of paper became the model for a metal plate that would go inside every Macintosh computer.
It's kind of a strange thing to sign the inside of a computer, especially one that was not really user-serviceable. Why did Steve Jobs want to have the entire team sign it? In a word, art.
For Jobs, the original Macintosh was not just a computer; it was a piece of art. It was the first mainstream computer to have a graphical user interface, and the team had employed a number of people who had artistic qualities as well as technical ones.
As all great artists sign their work, Jobs thought, so should the Mac team sign the piece of art computer they had made.