Ontologies form the basis of knowledge graphs, and taxonomies are often the basis of ontologies. Thus, a good understanding of taxonomy and ontology design best practices can go a long way. Following a brief introduction of definitions and examples, this session reviews standards and then goes beyond the standards to discuss practical considerations. Standards for ontologies are purely technical and don’t explain how to make a good ontology. Standards for “taxonomies” do not exist, but standards for thesauri are applicable to taxonomies and explain how to design them well. Best practices include basing the taxonomy and ontology on the content set to be retrieved and on use cases of search and retrieval of the intended users. Other topics discussed include the size, hierarchical depth and specificity of the taxonomy terms, the number of classes and specificity of relationships in an ontology, and the names of labels.