Corruption is a mechanic in the campaign mode of Total War: Warhammer and its sequels. Corruption represents the dark influence of certain nefarious factions in a province on the campaign map. Excessive corruption in a province usually benefits the spreading race, while harming other races.
In addition to corruption, many factions spread 
Untainted also known as Corruption reduction.
Each game implements Corruption differently. With the most major changes being between II and III. To avoid confusion, this page was split into three: