Cathode is
negative terminal or electrode through which electrons enter a direct
current load, such as an electrolytic
cell and the positive terminal of a battery or other source of electrical energy
through which they return. This terminal corresponds in electrochemistry to the terminal at which reduction
occurs. Within a gas discharge tube, electrons travel away from the cathode,
but positive ions (current carriers) travel toward the cathode.
Anode is
the terminal or electrode from which electrons leave a system.
In a battery or other source of direct current the
anode is the negative terminal, but in a passive load it is the positive
terminal. For example, in an electron
tube electron from the cathode travel across the tube toward the
anode, and in an electroplating cell negative ions are deposited at the
anode.