Reservoir simulation is a computational technique used to model the behavior of fluids within underground reservoirs, such as oil and gas fields. By using mathematical equations, it helps predict how these fluids will move over time, considering factors like pressure, temperature, and rock properties. This simulation aids engineers in making informed decisions about extraction methods and resource management. The process involves creating a digital representation of the reservoir, incorporating geological data and fluid characteristics. Reservoir simulation can optimize production strategies, reduce costs, and minimize environmental impacts, making it a vital tool in the energy industry.