The method of maximum likelihood, developed by R. A. Fisher in 1921, is a powerful tool for estimating parameters in various fields like genetics and bioassay. It is the oldest and most efficient method of estimation, providing consistent, unbiased, and asymptotically most efficient estimators. The method has been shown to have all the properties of the best estimation method, with applications in practical scenarios. The likelihood ratio test, based on a sufficient statistic, is frequently unbiased and the most powerful test available.