D-Brane Instantons in Type II Orientifolds

We review recent progress in determining the effects Of D-brane instantons in N = 1 supersymmetric compactifications of Type II string theory to four dimensions. We describe the abstract D-brane instanton calculus for holomorphic couplings such as the superpotential, the gauge kinetic function, and higher fermionic F-terms, and we briefly discuss the implications of background fluxes for the instanton sector. We then summarize die concrete consequences of stringy D-brane instantons for the construction of semirealistic models of particle physics or supersymmetry breaking in compact and noncompact geometries.