The taxonomy and classification of the genus Cannabis have been subjects of extensive debate, shaped by both traditional and modern approaches. This chapter reviews key methods, including biological, biochemical, legal, and genetic approaches, and examines how the expansion of the Cannabaceae family has redefined Cannabis within a broader phylogenetic context. Various classification systems are discussed, from early frameworks to modern genomic methods, with a focus on how the proliferation of cannabinoid-based systems has complicated the debate. The increasing availability of sequencing and molecular markers has been pivotal in differentiating species and subspecies, but researchers now face the challenge of integrating diverse phenotypic and chemotypic data. While machine learning offers potential solutions, this chapter emphasizes the need for interdisciplinary methods that combine these data sources, paving the way for a more accurate and holistic understanding of Cannabis taxonomy.