INTRODUCTION: The increasing incidence of cutaneous melanoma and the still limited effective treatments available for this disease represent a major health problem and a great challenge for research. The raise of the "omics" era and the development of new techniques to explore phenotypic heterogeneity are helping to decipher the mechanisms at the basis of melanoma heterogeneity.AREAS COVERED: We reviewed the most recent publications about the biology of cutaneous melanoma, to provide an overview of the most recent insights into the complexity of this tumor and their potential impact in the clinical settings. Expert commentary: Starting from the first attempts to provide a molecular classification of melanoma, it has been evident that this tumor represents a widely heterogeneous disease. This complexity and the multivariate nature of melanoma represent a major obstacle in developing the best management strategies for patients.