This article by Minoru Kanehisa, a leading figure in bioinformatics, discusses the development and significance of the KEGG (Kyoto Encyclopedia of Genes and Genomes) resource. KEGG is a comprehensive database that integrates genomic, chemical, and biological pathway information to facilitate the understanding of cellular organisms. The author highlights the evolution of bioinformatics from the 1970s to the present, emphasizing the role of high-throughput technologies and large-scale datasets. KEGG, initiated in 1995, aims to reconstruct biological systems from genome information, focusing on metabolic, signaling, and cellular processes. The article explains the concept of pathway mapping, which links genes to gene products and pathways, and the use of generalized protein-protein interactions and functional grouping (KOs) to extend experimental knowledge across different organisms. KEGG also integrates genomics and chemistry through metabolic pathway modules and reaction modules, enabling the analysis of co-evolutionary networks. The article further discusses the expansion of KEGG into a broader resource, including health information and translational bioinformatics, particularly through KEGG MEDICUS, which supports drug discovery and disease understanding. Finally, Kanehisa reflects on the hierarchy of data, information, and knowledge, emphasizing the importance of manual verification and the potential for uncovering fundamental principles of biological systems.This article by Minoru Kanehisa, a leading figure in bioinformatics, discusses the development and significance of the KEGG (Kyoto Encyclopedia of Genes and Genomes) resource. KEGG is a comprehensive database that integrates genomic, chemical, and biological pathway information to facilitate the understanding of cellular organisms. The author highlights the evolution of bioinformatics from the 1970s to the present, emphasizing the role of high-throughput technologies and large-scale datasets. KEGG, initiated in 1995, aims to reconstruct biological systems from genome information, focusing on metabolic, signaling, and cellular processes. The article explains the concept of pathway mapping, which links genes to gene products and pathways, and the use of generalized protein-protein interactions and functional grouping (KOs) to extend experimental knowledge across different organisms. KEGG also integrates genomics and chemistry through metabolic pathway modules and reaction modules, enabling the analysis of co-evolutionary networks. The article further discusses the expansion of KEGG into a broader resource, including health information and translational bioinformatics, particularly through KEGG MEDICUS, which supports drug discovery and disease understanding. Finally, Kanehisa reflects on the hierarchy of data, information, and knowledge, emphasizing the importance of manual verification and the potential for uncovering fundamental principles of biological systems.