The Pareto principle, also known as the 80/20 rule, suggests that roughly 80% of outcomes or outputs come from 20% of causes or inputs. This principle is named after Vilfredo Pareto, an Italian economist who observed that 80% of the land in Italy was owned by 20% of the population. The Pareto principle is used in business to focus efforts on the most important 20% of activities, customers or products that account for the majority of outcomes.