It is suggested that, in addition to data, information and knowledge, the information sciences should focus on understanding, understood as a higher-order knowledge, with coherent and explanatory potential. The limited ways in which understanding has been addressed in the design of information systems, in studies of information behaviour, in formulations of information literacy, and in impact studies are briefly reviewed, and future prospects considered. The paper is an extended version of a keynote presentation given at the i3 conference in June 2015.