Important Notice

We have moved the curation and development of Systems Biology Ontology (SBO) from this site to a GitHub repository The SBO OWL file will not be updated on this site anymore. This site will be fully retired in late Spring 2022 and API will not be accessible after that.

The most recent SBO OWL file is available at SBO terms can be browsed through the Ontology Lookup Service (OLS) webpage Follow the documentation at to use API to access OLS web services.

The SourceForge SBO project has also been retired. Please use the GitHub issue tracker to request the addition of new terms.

We apologise for any inconvenience this may cause.

The Systems Biology Ontology is a set of controlled, relational vocabularies of terms commonly used in Systems Biology, and in particular in computational modelling. It consists of seven orthogonal vocabularies defining: reaction participants roles (e.g. "substrate"), quantitative parameters (e.g. "Michaelis constant"), classification of mathematical expressions describing the system (e.g. "mass action rate law"), modelling framework used (e.g. "logical framework"), the nature of the entity (e.g. "macromolecule"), the type of interaction (e.g. "process"), as well as a branch to define the different types of metadata that may be present within a model.

SBO terms can be used to introduce a layer of semantic information into the standard description of a model, or to annotate the results of biochemical experiments in order to facilitate their efficient reuse. SBO is an Open Biomedical Ontologies (OBO) candidate ontology, and is free for use. More information about SBO can be found in the FAQ.

SBO is a project of the effort and is developed through community collaboration.