The objective of the Gene Ontology (GO) Consortium [GO] is to provide controlled vocabularies to describe specific aspects of gene products. Collaborating databases annotate their gene products (or genes) with GO terms, providing references and indicating what kind of evidence is available to support the annotations. The use of common GO terms by these databases facilitates uniform queries across them. The GO ontologies are structured to allow both attribution and querying to be performed at different levels of granularity. The GO vocabularies are dynamic, since knowledge of gene and protein roles in cells is accumulating and changing.

The three organizing principles of the GO are molecular function, biological process, and cellular component. A gene product has one or more molecular functions and is used in one or more biological processes; it may be, or may be associated with, one or more cellular components. Definitions