What describes the reaction between two dissimilar metals that touch each other?

The reaction between two dissimilar metals that touch each other is best described by electrolysis. When two different types of metals come into contact, especially in the presence of an electrolyte (like moisture), a galvanic cell can be formed. This cell creates a potential difference between the metals, causing electrons to flow from one metal to the other. As a result of this flow, one metal may corrode faster than it normally would in a non-electrolytic environment. This process can lead to significant deterioration of the less noble metal, while the more noble metal remains protected.

In this context, the term corrosion often refers to the general degradation of metals due to chemical reactions, while electrolysis specifically highlights the electrical aspect of the reaction occurring between the dissimilar metals and the influence of external factors like moisture. This makes electrolysis the more precise term in this scenario.