The Chern-Simons Structure of String Field Theory.

The generalized Chern-Simons structure of string field theory models represents the central thread that connects much of the work in this field. An analysis is made of the recent progress in string field theory with special emphasis on this structure. Open bosonic strings represent the template string model. At present we have a successful covariant, gauge invariant interacting field theory of these strings. We know how to gauge-fix it and extract the correct Feynman rules. Tree level predictions of the model are found to be in agreement with dual model amplitudes. The path integral measure (loop diagrams) is determined by imposing BRST invariance of the generating functional. In the process we determine some of the properties of the string gauge algebra. The cubic formulation of string field theory is reviewed. This formulation is independent of the dimension, metric and topology of space-time. As such, strings are keeping with the spirit of 3 dimensional metric independent gauge theories (Chern-Simons theories). The open questions of the model (non-locality, lack of Hamiltonian formalism, unitarity, underlying dynamical symmetry principle) are analyzed. Wherever bosonic strings ultimately lead us we will have gotten there in no small part due to the succes we have had in casting it in a Chern-Simons form.