Genetic interaction refers to the way different genes influence each other's effects on an organism's traits or characteristics. When two or more genes interact, they can produce a combined effect that is different from the sum of their individual effects. This can lead to variations in traits, such as color, size, or disease susceptibility, depending on how the genes work together. These interactions can be classified into several types, including epistasis, where one gene masks the effect of another, and additive interactions, where the effects of multiple genes combine to influence a trait. Understanding genetic interactions is crucial in fields like genetics, evolution, and medicine, as they help explain complex traits and diseases.