Research in theoretical elementary particle physics will be concerned with superstrings (which are one - dimensional objects) and their higher - dimensional generalizations, known as super p - branes. In particular, the role of these objects as effective, long-distance descriptions of topological defects in supersymmetric quantum field theories will be explored. The theory of superstrings shows promise as a theory which would describe all of the forces of nature, including gravity. Supersymmetry relates the particles which make up matter to those which carry the forces between bits of matter. The study of strings and their generalizations as topological defects has proved to be of importance in elucidating the nature of string theory.