The notion of a schema and the related notions of beta structures, frames, scripts, plans, and so on have formed the focus of research in Cognitive Science over the past 3 or 4 years, (cf. Bobrow & Norman, 1975; Chafe, 1976; Minsky 1975; Moore & Newell, 1973; Rumelhart, 1975; Schank & Abelson, 1975; Winograd, 1975). In this paper, I introduce these concepts to those unfamiliar with them and show why so much attention has been paid to them. These various terms have been used by different authors to refer to any of a set of interrelated concepts. These terms are not all synonymous. Different authors have different things in mind when they use these different terms. Nevertheless, the various concepts are closely enough related that a discussion of any one of them will serve as an introduction to the others. I thus focus my discussion on the one I know best, schemata (the singular is schema), as developed in Rumelhart and Ortony (1977).