This paper discusses D-branes, quivers, and ALE instantons in the context of type I and II superstring theories. D-branes located at points in the orbifold $ C^2/Z_n $ are described by supersymmetric gauge theories whose field content is summarized by a 'quiver diagram'. These theories include non-metric couplings to the orbifold moduli, particularly twisted sector moduli that couple as Fayet-Iliopoulos terms in the gauge theory. The theories describe D-branes on resolved ALE spaces, whose vacua are moduli spaces of smooth ALE metrics and Yang-Mills instantons, explicitly computable. For $ U(N) $ instantons, the construction exactly reproduces results of Kronheimer and Nakajima. The paper introduces the concept of D-branes on orbifolds of $ C^2 $, discussing the closed string spectrum and gravitational moduli on ALE spaces. It reviews the properties of ALE spaces and their relation to orbifolds of $ C^2 $, and discusses the sigma model on ALE spaces. The paper then considers the massless spectrum of type II string theories, including IIa, IIb, and I, and describes the massless closed string sector of the type I string. The paper also discusses the addition of Dirichlet 5-branes, the consistency conditions on the matrices $ \gamma(g), \gamma(\Omega) $, and the algebraic consistency conditions. It introduces quiver diagrams to summarize the field content of the SYM theory on the p-brane, and discusses the canonical form for $ \gamma(\Omega) $. The paper then considers the DD and DN spectrum for $ (p, p + 4) $ configurations at the fixed point, and describes the world-volume action for p-branes transverse to the fixed point. It discusses the Chern-Simons couplings and the supersymmetric completion of the action, and concludes with the hyperkähler moment map. The paper provides a detailed analysis of the effective field theories for D-branes on ALE spaces, and their relation to instanton moduli spaces.This paper discusses D-branes, quivers, and ALE instantons in the context of type I and II superstring theories. D-branes located at points in the orbifold $ C^2/Z_n $ are described by supersymmetric gauge theories whose field content is summarized by a 'quiver diagram'. These theories include non-metric couplings to the orbifold moduli, particularly twisted sector moduli that couple as Fayet-Iliopoulos terms in the gauge theory. The theories describe D-branes on resolved ALE spaces, whose vacua are moduli spaces of smooth ALE metrics and Yang-Mills instantons, explicitly computable. For $ U(N) $ instantons, the construction exactly reproduces results of Kronheimer and Nakajima. The paper introduces the concept of D-branes on orbifolds of $ C^2 $, discussing the closed string spectrum and gravitational moduli on ALE spaces. It reviews the properties of ALE spaces and their relation to orbifolds of $ C^2 $, and discusses the sigma model on ALE spaces. The paper then considers the massless spectrum of type II string theories, including IIa, IIb, and I, and describes the massless closed string sector of the type I string. The paper also discusses the addition of Dirichlet 5-branes, the consistency conditions on the matrices $ \gamma(g), \gamma(\Omega) $, and the algebraic consistency conditions. It introduces quiver diagrams to summarize the field content of the SYM theory on the p-brane, and discusses the canonical form for $ \gamma(\Omega) $. The paper then considers the DD and DN spectrum for $ (p, p + 4) $ configurations at the fixed point, and describes the world-volume action for p-branes transverse to the fixed point. It discusses the Chern-Simons couplings and the supersymmetric completion of the action, and concludes with the hyperkähler moment map. The paper provides a detailed analysis of the effective field theories for D-branes on ALE spaces, and their relation to instanton moduli spaces.