Deterministic models are mathematical representations that predict outcomes with certainty, given a specific set of initial conditions. These models operate under the assumption that the same input will always produce the same output, making them reliable for simulations in various fields such as physics, engineering, and economics. In contrast to stochastic models, which incorporate randomness and uncertainty, deterministic models provide clear and precise results. They are often used for tasks like weather forecasting or financial projections, where understanding the exact relationship between variables is crucial for decision-making and planning.