Now, in this lecture, we're going to talk about something called electrochemical cells, also known as Galvanic cells. Now, recall that redox reactions are chemical reactions in which electrons flow from one atom to another. From physics, we know that moving charge such as electrons can be used to do useful work. Therefore, the flow of electrons found in redox reactions can somehow be transformed to do useful work. So an electrochemical cell is simply a way to capture this useful work produced by the movement of electrons from one atom to another. Now, we're going to talk about special types of electrochemical cells called voltaic cells, also known as batteries.