As our understanding of Acute Myeloid Leukemia (AML) has grown, so too have the classification systems for the disease evolved. Initially, the 'FAB classification' system, based on cell morphology (the structural appearance of the cell), was widely used. This system included eight subtypes from M0 to M7 (M0, M1, M2, M3, M4, M5, M6, M7), with subtypes other than M3 having similar treatment approaches. However, after the critical role of genetic and molecular abnormalities in the pathogenesis and clinical course of the disease was understood, the World Health Organization (WHO) developed a genetically based classification. The WHO classification has been updated in 2008, 2016, and 2022. In the latest update, specific subtypes are defined for each genetic anomaly, and for certain specific genetic disorders, the blast percentage (leukemic cell percentage) required for disease diagnosis has been reduced from 20% to 10%.