What is the Pareto Principle and how is it applied in various fields?

The Pareto Principle, also known as the 80/20 rule, suggests that 80% of effects come from 20% of causes. It was formulated by economist Vilfredo Pareto in the early 20th century. The principle is often applied in economics and can be observed in various systems, particularly linear systems where a small number of inputs lead to the majority of outputs. However, the principle does not always hold true in nonlinear systems, where the relationship between effort and outcome can be unpredictable.