The 80\20 rule, also known as the Pareto Principle, is an aphorism which asserts that 80% of outcomes (or outputs) result from 20% of all causes (or inputs) for any given event. In business, a goal of the 80\20 rule is to identify inputs that are potentially the most productive and make them the priority. The 80/20 relationship theory states that you can only get about 80% of your wants and needs from a healthy relationship, while the remaining 20% you need to provide for yourself.