Every portable electronic device is fueled by chemistry, specifically through oxidation-reduction or redox reactions. In redox reactions, one compound gains electrons (reduction) and one compound loses them (oxidation). Chemists can set up reactions so that electrons are forced to move in a certain way to create an electrical current. Metals often play a key role in redox reactions, which are essential to all aspects of chemistry, particularly in many biochemical processes. Part of the series Chemistry: Challenges And Solutions.