title: In this issue: Ontologies a key concept in informatics and key for open definitions of cases, exposures, and outcome measures.
authors.affiliation: University of Surrey, Guildford, UK.
authors.forename: Simon
authors.initials: S
authors.lastname: de Lusignan
mesh_terms: D064229:Biological Ontologies; D057286:Electronic Health Records; D066275:Health Information Exchange; D006801:Humans; D012660:Semantics