The Pareto principle (also known as the 80/20 rule, the law of the vital few) states that, for many events, roughly 80% of the effects come from 20% of the causes. It was named after the founder Vilfredo Pareto, in 1895. He noticed that people in society seemed to separate into what he titled the “vital few,” or the top 20% in terms of money and influence, and the “trivial many,” or the bottom 80 percent. Eventually his work was converted into The 80/20 Principle: The Secret of Achieving More with Less by Richard Kock.
This is often used by many successful professionals across various fields and can be useful to prioritize tasks, days, weeks, and months.
How can you use this in everyday life?
If you have a to-do list with ten items on it, prioritize the top two tasks that you deem to be the most important. In the majority of cases these are the ones you least want do and therefore you will end up procrastinating and focus on the less meaningful tasks for that given period of time.
You could also consider applying it to your income, if for instance you work in sales, you could focus putting 80% of your time into the top 20% of your income sources.