Why is OPEC important?

Answer 1

The "Organization of Petroleum Exporting Countries" (OPEC) includes most of the world's major oil-exporting countries. By agreeing to limit their respective production levels, they maintain a higher price for their oil worldwide. While this extends the life of their domestic fields, and provides substantial income, it is a semi-monopoly that limits the affordability of petroleum in many of the world's developing countries. There is no international law that prohibits such cartels, as would apply within many countries.

(In the past, such attempts to control the worldwide production of raw materials would have almost certainly led to conquest of these areas by militarily stronger countries.)