OGG is a biological ontology in the area of genes and genomes. OGG uses the Basic Formal Ontology (BFO) as its upper level ontology. This OGG document contains the genes and genomes of a list of selected organisms. Each gene in OGG has over 10 annotation items, includes gene-associated Gene Ontology (GO) and PubMed article information. OGG has represented genes in human, two viruses, and four bacteria. Additionally, 7 OGG subsets are developed to represent genes and genomes of 7 model systems including mouse, fruit fly, zebrafish, yeast, A. thaliana, C. elegans, and P. falciparum.