The Gene Ontology, or GO, project can be broadly split into two parts. The first is the ontology itself, a controlled vocabulary of terms split into three related ontologies covering basic areas of Molecular biology: the molecular function of gene products, their role in multi-step biological processes, and their localization to cellular components. The ontology is continuously updated, and new versions are made available on a monthly basis.

The second part is annotation, the characterization of gene products using terms from the ontology. The members of the GO Consortium submit their data and it is made publicly available through the GO website.