Estimation techniques are methods used to make educated guesses about unknown values or quantities. These techniques are commonly applied in fields like project management, finance, and engineering to predict costs, durations, or resource needs. By using historical data, expert judgment, and statistical methods, estimators can provide a range of possible outcomes to aid decision-making. Common estimation techniques include analogous estimating, where past project data is used to inform current estimates, and parametric estimating, which relies on statistical relationships between variables. Other methods, such as three-point estimation, consider best-case, worst-case, and most likely scenarios to improve accuracy.