  In these talks we review some of the recent results on open strings and
noncommutative gauge theories, starting from the early calculations of open
strings in a constant electromagnetic background. We discuss both the neutral
string and the charged string. In the latter case, the scaling limit that leads
to noncommutative abelian gauge theory can be generalized to a scaling limit in
which multiple noncommutativity parameters enter. Our approach corresponds to
expanding a theory with U(N) Chan-Paton factors around a background U(1)^N
gauge field with different magnetic fields in each U(1). This scaling limit can
be interpreted in terms of a matrix model. We also describe an open string
model with a time-dependent noncommutativity parameter. This model is the open
string version of a WZW model based on a non-semi-simple group. It has a
time-dependent background, and a spacetime metric of the plane wave type
supported by a Neveu-Schwarz two-form potential.
