Peak oil is described as the moment at which economically viable extraction of petroleum starts to permanently decrease. Since the amount of oil on Earth is limited, eventually peak oil production will be reached.

The concept of peak oil was introduced by the American geologist Marion King Hubbert in 1956. He predicted the peak oil production in the USA to happen between 1965 and not later than 1970. By the late 70s, there was a peak that functioned as a local peak. For the whole world, he predicted the peak oil production in 2000, with oil extraction of 12.5 billion barrels per year (34 million barrels per day). However, the oil production in 2000 was 75 million barrels per day, more than twice that amount, and continued to grow till at least 2019.

In the past, some experts have said that peak oil has already been reached or will soon be reached. For example, geologist Kenneth S. Deffayes stated in February 2006 that world oil production peaked on December 16, 2005. Colin Campbell, a British geologist, predicted that the world oil production would peak in 2007. On the other hand, as per 2007, the U.S. Department of Energy predicted that the peak won't happen until 2037.

According to Our World in Data, the historical maximum oil production of 52,182 TWh was achieved in 2018. In 2019-2021 it was 52,075, 48,508, and 49,094 TWh. Therefore, the peak was either reached in 2018 or will be reached in 2022 or later.