From twists and shifts to L-R asymmetric D-branes

In the first part of the talk, we discuss non-geometric twists and shifts and briefly review asymmetric orbifolds and free fermion constructions. These allow us to build Type IIB models with N = 1(L) + 1(R) and N = 1(L) + 0(R) models having few or no moduli. We then consider unoriented projections of the former and ('exotic') D-branes in the latter.In the second part, devoted to L-R asymmetric D-branes, we review how extended supergravity vacua in D = 4 can be embedded in Type II superstrings. We then identify bound states of D-branes with residual susy and non-trivial R-R couplings. We discuss the N = 6 = 2(L) + 4(R) case in detail and sketch other extended susy cases. Finally we describe the resulting open string excitations.We conclude with some speculations and possible interesting developments.