How do anticorrosion systems work?

I know there are several different kinds of systems. We have cathodic systems and impressed current systems where I work, but I don’t have the slightest clue how/why they work. Maybe a more specific question would be, how are (metal) corrosion and electric current related?

:smack: Maybe I should go to the right forum before I click ‘New Thread.’ Could someone kindly move this? Sorry.

The only system I know much about is the kind that is used on boat motors and water heaters called a “sacrificial anode”. This is a piece of zinc attached to the engine via a grounding wire used to protect against galvanic corrosion(corrosion that happens when two different metals are placed together in an electrolyte). As electrical curreent passes out of the zinc anode into the water (the electrolyte, in this case (especially seawater!)) the anode dissolves ions into the water(corrodes). When the anode is nearly completely corroded, you can just attatch a new one, saving the rest of the engine or water heater from corroding.