Closed String Field Theory: An Introduction

In these introductory notes I explain some basic ideas in string field theory. These include: the concept of a string field, the issue of background independence, the reason why minimal area metrics solve the problem of generating all Riemann surfaces with vertices and propagators, and how Batalin-Vilkovisky structures arise from the state spaces of conformal field theories including ghosts. More advanced topics and recent developments are summarized. (To appear in the proceedings of the 1992 Summer School at Les Houches.)}