Pareto chart is a visual representation of the Pareto Rule.
Pareto Rule, which is also popularly known as 80/20 rule, was coined by Italian mathematician Vilfredo Pareto. He stated that 20% of the population owns 80% of the land.
Later, the quality guru Joseph Juran changed to 80% of the problems is due to 20% of the reasons.
In simple words, the Pareto rule is all about prioritizing the vital few from the trivial many.
This video shows the steps involved to create a Pareto chart in Excel.