Functional Requirements for Bibliographic Records (FRBR) is a conceptual model underlying the new cataloguing standard RDA. It models the bibliographic universe independently of any cataloguing code or implementation. Bibliographic data are described based on a set of interconnected entities concerning the intellectual content, the physical production and dissemination, and the subjects of bibliographic records. This chapter presents the entities, the user tasks, the direct and indirect relationships defined in FRBR and explains them through examples. An overview of the Functional Requirements for Authority Data (FRAD) is also given.