How has the classification kingdom system changed over the last 300 years?

Over the last 300 years, the classification kingdom system has evolved significantly, particularly with the advent of modern genetics and molecular Biology. Initially, organisms were classified primarily based on morphological characteristics, leading to a relatively simple two-kingdom system of Animalia and Plantae. As research advanced, particularly in the 19th and 20th centuries, the five-kingdom system emerged, adding Fungi, Protista, and Monera. Recently, the introduction of genetic data has further refined classifications, leading to the three-domain system (Bacteria, Archaea, Eukarya) that reflects evolutionary relationships more accurately.