KEGG is a comprehensive database that integrates genomic, chemical, and systemic functional information to link genomes to life and the environment. It provides reference knowledge bases for linking genomes to life through PATHWAY mapping and to the environment through BRITE mapping. KEGG PATHWAY includes a new global map of metabolic pathways, combining about 120 existing pathway maps. KEGG MODULE defines and stores smaller pathway modules and other functional units. KEGG DRUG contains all approved drugs in the US and Japan, while KEGG DISEASE links disease genes, pathways, drugs, and diagnostic markers. KEGG is expanding to meet practical application needs, including chemical genomics and metagenomics. The KEGG project began in 1995, coinciding with the sequencing of the first free-living organism's genome. KEGG PATHWAY serves as a reference knowledge base for understanding higher-level functions of cellular processes and organism behaviors from large-scale molecular data sets. KEGG BRITE, an ontology database, represents functional hierarchies of various biological objects and their relationships. KEGG GENES is used as a reference database for genome annotation, with KO (KEGG Orthology) identifiers assigned to genes. KEGG uses KO assignments to annotate new genomes, involving computational and manual steps. The KO system links genomes to biological systems through pathway and BRITE mapping. KEGG also supports chemical annotation, linking genomic or transcriptomic data to chemical structures. KEGG PATHWAY has been expanded with new pathway maps, including signal transduction, cellular processes, and human diseases. KEGG MODULE is a new database that collects pathway modules and other functional units. KEGG is accessible via GenomeNet and a new website, and is supported by various Japanese research institutions. KEGG is used for medical and pharmaceutical applications, including disease pathway maps and drug information.KEGG is a comprehensive database that integrates genomic, chemical, and systemic functional information to link genomes to life and the environment. It provides reference knowledge bases for linking genomes to life through PATHWAY mapping and to the environment through BRITE mapping. KEGG PATHWAY includes a new global map of metabolic pathways, combining about 120 existing pathway maps. KEGG MODULE defines and stores smaller pathway modules and other functional units. KEGG DRUG contains all approved drugs in the US and Japan, while KEGG DISEASE links disease genes, pathways, drugs, and diagnostic markers. KEGG is expanding to meet practical application needs, including chemical genomics and metagenomics. The KEGG project began in 1995, coinciding with the sequencing of the first free-living organism's genome. KEGG PATHWAY serves as a reference knowledge base for understanding higher-level functions of cellular processes and organism behaviors from large-scale molecular data sets. KEGG BRITE, an ontology database, represents functional hierarchies of various biological objects and their relationships. KEGG GENES is used as a reference database for genome annotation, with KO (KEGG Orthology) identifiers assigned to genes. KEGG uses KO assignments to annotate new genomes, involving computational and manual steps. The KO system links genomes to biological systems through pathway and BRITE mapping. KEGG also supports chemical annotation, linking genomic or transcriptomic data to chemical structures. KEGG PATHWAY has been expanded with new pathway maps, including signal transduction, cellular processes, and human diseases. KEGG MODULE is a new database that collects pathway modules and other functional units. KEGG is accessible via GenomeNet and a new website, and is supported by various Japanese research institutions. KEGG is used for medical and pharmaceutical applications, including disease pathway maps and drug information.