The Human Phenotype Ontology (HPO) graph is a standardized vocabulary of human phenotypic abnormalities and their relationships. It represents these abnormalities as nodes in a graph, with edges indicating relationships such as subtypes or overlapping features. The HPO graph is organized in a hierarchical structure, with more general terms at the top and more specific terms at the bottom. The ontology provides a framework for the annotation of human genetic variations, aiding in the diagnosis of rare genetic disorders and the identification of potential therapeutic targets.