An oil well is a structure created to extract crude oil from underground reservoirs. It involves drilling deep into the earth's surface to reach oil deposits, which are often found in rock formations. Once the well is drilled, various methods are used to bring the oil to the surface, including pumping and natural pressure. Oil wells can vary in depth and design, depending on the location and the geology of the area. They are typically found in regions rich in fossil fuels, such as the Middle East, North America, and Russia. The extracted oil is then transported for refining and distribution.