The Organization of the Petroleum Exporting Countries is an intergovernmental organization of 13 nations, founded on 14 September 1960 in Baghdad by the first five members (Iran, Iraq, Kuwait, Saudi Arabia, and Venezuela), and headquartered since 1965 in Vienna Austria. This Organization was established by countries that controlled more than 50% of the world oil and more than 85% proven oil reserves. Thus was the beginning of a cartel that had a great influence on the world oil market and indirectly on the world economy.
OPEC was an organization established to control oil prices by forcing its members to limit oil production. Less production would mean higher oil prices.
In addition to the OPEC members, the following 10 more oil-exporting countries, led by Russia mainly, are grouped as OPEC+ cartel from the year2016 as they cooperate in fixing the global crude oil prices by agreeing to production quotas so that global production is below the global demand/consumption. OPEC+ countries encourage unnecessary excess capital investment in the global oil sector instead of encouraging their cheaper oil production at lower capital investment.