This book presents a self-contained introduction to the analytic foundation of a level set method for various surface evolution equations including curvature flow equations. These equations are important for many fields of applications, such as material sciences, image processing and differential geometry. The goal is to introduce a generalized notion of solutions allowing singularities, and to solve the initial-value problem globally-in-time in a generalized sense. Various equivalent definitions of solutions are studied. Several new results on equivalence are also presented. Further, a...