The idea behind the 80:20 rule is that 80% of the results come from 20% of the work. More formally, 80% of the effects, come from 20% of the causes. The origin of this idea came from Vincent Pareto who discovered that 80% of the land in Italy, was owned by 20% of the people. Of course, the exact percentage doesn’t always hold up, but the application of this idea is to prioritize and focus on the relevant things.