Oil reserves refer to the quantities of crude oil that can be extracted from the ground using current technology and under existing economic conditions. These reserves are classified into proven, probable, and possible categories, indicating the likelihood of extraction. Proven reserves are the most certain, while probable and possible reserves have a lower degree of certainty. Countries with significant oil reserves, such as Saudi Arabia and Venezuela, play a crucial role in the global energy market. The amount of oil reserves can influence a nation's economy, energy policies, and geopolitical relationships, as countries with large reserves often have more leverage in international affairs.