It seems， then， quite likely that a twentyfirst-century particle physicist will re-quire a working knowledge of supersymmetry and string theory， and in writing this extl hope to provide this. The first part of the textis a review of the Standard Model.It is meant to complement existing books， providing an introduction to perturbative ind phenomenological aspects of the theory， but with a lengthy introduction to ion-perturbative issues， especially in the strong interactions. The goal is to provide m understanding of chiral symmetry breaking， anomalies and instantons， suitable ror thinking about possible strong dynamics， and about dynamical issues in super-；ymmetric theories. The first part also introduces grand unification and magnetic rnonopoles.
　　The second part of the book focuses on supersymmetry. In addition to global su-persymmetry in superspace， there is a study of the supersymmetry currents， which are important for understanding dynamics， and also for understanding the BPS con-ditions which play an important role in field theory and string theory dualities. The MSSM is developed in detail， as well as the basics of supergravity and supersym-metry breaking. Several chapters deal with supersymmetry dynamics， including dynamical supersymmetry breaking， Seiberg dualities and Seiberg-Witten theory.The goal is to introduce phenomenological issues （such as dynamical supersymme-try breaking in hidden sectors and its possible consequences）， and also to illustrate the control that supersymmetry provides over dynamics.
　　I then turn to another critical element of beyond the Standard Model physics：general relativity， cosmology and astrophysics. The chapter on general relativity is meant as a brief primer. The approach is more field theoretic than geometrical， and the uninitiated reader will learn the basics of curvature， the Einstein Lagrangian，the stress tensor and equations of motion， and will encounter the Schwarzschild solution and its features. The subsequent two chapters introduce the basic features of the FRW cosmology， and then very early universe cosmology： cosmic history，inflation， structure formation， dark matter and dark energy. Supersymmetric dark matter and axion dark matter， and mechanisms for baryogenesis， are all considered.
　　The third part of the book is an introduction to string theory. My hope， here， is to be reasonably comprehensive while not being excessively technical. These chapters introduce the various string theories， and quickly compute their spectra and basic features of their interactions. Heavy use is made of light cone methods. The full machinery of conformal and superconformal ghosts is described but not developed in detail. but conformal field theory techniques are used in the discussion of string interactions. Heavy use is also made of effective field theory techniques， both at weak and strong coupling. Here， the experience in the first half of the text with supersymmetry is invaluable； again supersymmetry provides a powerful tool to constrain and understand the underlying dynamics. Two lengthy chapters deal with string compactifications； one is devoted to toroidal and orbifold compactifications，which are described by essentially free strings； the other introduces the basics of Calabi-Yau compactification. Four appendices make up the final part of this book.