Introduction to Soft Collinear Effective Theory Among resummation techniques for perturbative QCD in the context of collider and flavor physics soft collinear effective theory (SCET) has emerged as both a powerful and versatile tool having been applied to a large variety of processes from B meson decays to jet production at the LHC. This book provides a concise pedagogical introduction to this technique. It discusses the expansion of Feynman diagrams around the high energy limit followed by the explicit construction of the effective Lagrangian first for a scalar theory then for QCD. The underlying concepts are illustrated with the quark vector form factor at large momentum transfer and the formalism is applied to compute soft gluon resummation and to perform transverse momentum resummation for the Drell Yan process utilizing renormalization group evolution in SCET. Finally the infrared structure of n point gauge theory amplitudes is analyzed by relating them to effective theory operators. This text is suitable for graduate students and non specialist researchers alike as it requires only basic knowledge of perturbative QCD.