  In these notes we review aspects of semi-realistic particle physics from the
point of view of type II orientifold compactifications. We discuss the
appearance of gauge theories on spacetime filling D-branes which wrap
non-trivial cycles in the Calabi-Yau. Chiral matter can appear at their
intersections, with a natural interpretation of family replication given by the
topological intersection number. We discuss global consistency, including
tadpole cancellation and the generalized Green-Schwarz mechanism, and also the
importance of related global $U(1)$ symmetries for superpotential couplings. We
review the basics of D-instantons, which can generate superpotential
corrections to charged matter couplings forbidden by the global $U(1)$
symmetries and may play an important role in moduli stabilization. Finally, for
the purpose of studying the landscape, we discuss certain advantages of
studying quiver gauge theories which arise from type II orientifold
compactifications rather than globally defined models. We utilize the type IIa
geometric picture and CFT techniques to illustrate the main physical points,
though sometimes we supplement the discussion from the type IIb perspective
using complex algebraic geometry.
