(Accepted for publication; final date unknown at present.) Boundary objects are abstract or physical artefacts that exist in the liminal spaces between adjacent communities of people. The theory of BOs was originally introduced by Star and Griesemer in a study on information practices at the Berkeley Museum of Vertebrate Zoology but has since been adapted in a broad range of research contexts in a large number of disciplines including the various branches of information science. The aim of this review article is to present an overview of the state of the art of information science research informed by the theory of BOs, critically discuss the notion, and propose a structured overview of how the notion has been applied in the study of information.