The Kyoto Encyclopedia of Genes and Genomes (KEGG) is a comprehensive database resource that integrates genomic, chemical, and systemic functional information. It links gene catalogs from sequenced genomes to higher-level systemic functions, such as cellular processes, organismal systems, and ecosystem functions. KEGG has developed a knowledge base for these systemic functions, including KEGG pathway maps, BRITE functional hierarchies, and KEGG modules. The KEGG Orthology system facilitates cross-species annotation by linking genes in genomes to molecular networks. KEGG Mapper is a set of tools for mapping KEGG PATHWAY, BRITE, and MODULE data, enabling the integration and interpretation of large-scale molecular data sets. Recent enhancements include the integration of disease and drug information, which are used in clinical practice and society, to support translational bioinformatics. This integration involves mapping disease genes and drug targets to KEGG pathway maps and BRITE hierarchies, enhancing the knowledge base and enabling better translation of research findings into medical and industrial innovations.The Kyoto Encyclopedia of Genes and Genomes (KEGG) is a comprehensive database resource that integrates genomic, chemical, and systemic functional information. It links gene catalogs from sequenced genomes to higher-level systemic functions, such as cellular processes, organismal systems, and ecosystem functions. KEGG has developed a knowledge base for these systemic functions, including KEGG pathway maps, BRITE functional hierarchies, and KEGG modules. The KEGG Orthology system facilitates cross-species annotation by linking genes in genomes to molecular networks. KEGG Mapper is a set of tools for mapping KEGG PATHWAY, BRITE, and MODULE data, enabling the integration and interpretation of large-scale molecular data sets. Recent enhancements include the integration of disease and drug information, which are used in clinical practice and society, to support translational bioinformatics. This integration involves mapping disease genes and drug targets to KEGG pathway maps and BRITE hierarchies, enhancing the knowledge base and enabling better translation of research findings into medical and industrial innovations.