The notion of stability of functional equations has been an area of revision and development for the past 20 years, having its origins more than half a century ago when S. Ulam posed the fundamental problem and D. H. Hyers gave the first significant partial solution. This volume is unique in that (to date) none exists as a comprehensive examination to the subject. The authors present both classical results and their original research in an integrated and self-contained fashion. Apart from the main topic of the stability of certain functional equations, related problems are discussed. These include the stability of the convex functional inequality and the stability of minimum points. The techniques used require some basic knowledge of functional analysis, algebra, and topology. The text could be used in graduate seminars or by researchers in the field.