Motivator-Hygiene Theory, proposed by Frederick Herzberg, is a psychological theory that suggests two sets of factors influence job satisfaction and motivation: motivators and hygiene factors. Motivators, such as achievement and recognition, lead to higher job satisfaction and increased motivation, while hygiene factors, like salary and working conditions, can prevent dissatisfaction but do not necessarily increase satisfaction when improved. This theory emphasizes the importance of understanding both types of factors to create a motivated and productive workforce.