The 80/20 Rule
The principle is named after the Italian economist Vilfredo Pareto (1848–1923). In 1896 he observed that roughly 80% of the land in Italy belonged to about 20% of the population. Quality-management pioneer Joseph M. Juran later generalized this observation into the well-known "80/20 rule": in many systems, roughly 20% of causes produce about 80% of the effect.
The exact numbers 80 and 20 aren't a law of nature but a rule of thumb — the core idea is that cause and effect are rarely distributed evenly. A small number of customers often generate most of the revenue, a small number of tasks most of the progress, a small number of decisions most of the impact.
Why this resonates with me
As an entrepreneur running several companies, this principle helps me prioritize every day: not every task deserves equal attention. Recognizing the decisive 20% and putting your energy there often achieves more than simply working through every item on a list — in business just as much as in everyday life.