Brothers Malcolm and Angus Young were looking for a name for their band when their sister, Margaret, saw the initials 'AC/DC' on the back of her sewing machine. The initials stand for 'alternating current/direct current,' which indicates the type of electricity the machine uses. The brothers felt this perfectly captured the high-voltage energy and raw power of their music. They adopted the lightning bolt logo to further emphasize the theme. AC/DC went on to become one of the most successful rock bands in history, with 'Back in Black' becoming the second best-selling album of all time.