The last five or six years have seen a substantial change in the nature of research into phonological theory. This change has been marked by the development of several new theoretical frameworks, for which we can use the somewhat awkward and misleading term "nonlinear phonology". In this short essay, I hope to give an introduction to the various ideas underlying nonlinear phonology, as well as to provide an outline of the mechanics of formal analysis under this rubric. Because of rigid constraints of space, I cannot do justice to every viewpoint, nor can I present full-fledged arguments. But I do try to provide something of a retro-spective on what has already been achieved and the reasons behind it, and I offer a lengthy bibliography to those whose interest is stimulated by this survey.
The structure of this presentation is as follows. In the first section I describe the basic notions of the theory in Chomsky and Halle (1968), particularly those less well-known features that are essential to understanding the subsequent development of non-linear phonology. In the following sections I characterize the two most important and extensive such nonlinear theories, the metrical and the autosegmental, including the topic ofsyllable structure in the former. The concluding section deals with a recent area of research, the unification of the autosegmental and metrical theories.