Describing the fundamental mechanism of most metallic corrosion, where an anodic reaction (metal dissolving and releasing electrons) is coupled with a cathodic reaction (an oxidizer consuming those electrons). Understanding this electron flow allows technicians to measure corrosion rates with a voltmeter and stop the degradation using cathodic protection.
Heard on the job
Rusting is an electrochemical process, which is why we can stop it by pumping direct current into the pipe.