What is OPEC?
OPEC is the Organization of the Petroleum Exporting Countries. It was founded in 1960 by Saudi Arabia, Venezuela, Iraq, Iran and Kuwait. The other countries that have joined OPEC since are Libya, the United Arab Emirates, Algeria, Nigeria, Ecuador, Gabon, Angola, Equatorial Guinea and the Republic of the Congo - bringing OPEC's membership to 14, as of January 2019.
For many commentators, OPEC is a cartel in the sense that it regulates the supply of oil in the hope of controlling the price. OPEC does this by holding biannual meetings to set the oil production quotas for its member countries.
In the past, OPEC's dominance over the production of oil meant that the organization was considered to be very powerful. However, the rise of the American fracking industry has raised questions about whether OPEC's control over the price of oil is weakening.