What is OPEC importance?

Answer 1

Organization of Petroleum Exporting Countries is an association of approx 12 countries, the principal oil producing countries, whose aim is to look after the interests of the member countries. There is not a fixed number of countries, and several have come and gone according to local circumstance. Notably Indonesia.

They set the price of crude oil on the world markets, and thus are of immense importance in world commerce.

Energy is a prime determinant of economic prosperity, and the most prosperous countries have a large energy demand. Not necessarily from Oil.

OPEC is mainly a benign organization, but when they have felt their interests have been threatened, they have not hesitated to step in with restricting the supply of oil.