the electrode potential

How badly does a given metal 'want' to give up its electrons and dissolve? The electrode potential is a voltage that measures exactly that tendency for one half-reaction. Because you can never measure a single electrode alone (a battery needs two ends), chemists agreed on a reference — the standard hydrogen electrode — and call its potential zero, then measure every other half-reaction against it. The result is a table of standard electrode potentials, quoted in volts, that ranks reactions by their pull toward reduction (gaining electrons).

Reading the table: a strongly positive potential means the reaction really wants to run in the reduction direction, so that metal is noble and resists corroding — gold's Au3+ + 3 electrons -> Au sits near +1.5 V, copper's Cu2+ + 2 electrons -> Cu at +0.34 V. A strongly negative potential means the metal much prefers to dissolve (oxidize): iron Fe2+ + 2 electrons -> Fe is -0.44 V, zinc -0.76 V, aluminum -1.66 V, magnesium -2.37 V. When two half-cells are joined, the difference in their potentials is the cell voltage driving the reaction, and the more negative electrode is the anode that corrodes. Iron next to copper has a driving voltage of about 0.34 - (-0.44) = 0.78 V pushing the iron to dissolve.

The honest caveat is that electrode potential tells you the DIRECTION and driving force of corrosion — whether it is thermodynamically possible — but says nothing about the SPEED. A reaction can be strongly favorable yet crawl because a protective film chokes it: aluminum has one of the most negative potentials, yet a soda can does not vanish, because its oxide film blocks the reaction almost completely. So potentials predict who wins the tug-of-war, while corrosion rate (kinetics) decides how fast, and the two must be read together.