Electrodes are conductive materials that allow electric current to enter or leave a medium, such as a solution or a gas. They are commonly made from metals like copper or platinum and are essential components in various devices, including batteries, electrolysis cells, and sensors. In a battery, for example, one electrode is the anode, where oxidation occurs, while the other is the cathode, where reduction takes place. The flow of electrons between these electrodes generates electrical energy, powering devices like smartphones and electric vehicles.