Repurposed inventions take recycling to a whole new level by using and improving upon existing technologies. In this section, learn about creative invention mashups and how inventions evolve over time.
How 2-D Bar Codes Work
Bar codes have grown up in a big way since they hit the market with a bang (or a beep) in the 1970s. Now all you have to do is whip out your smartphone and point it at the nearest 2-D bar code. It may contain a message just for you, dear consumer.