The book "An Introduction to the Theory of Functional Equations and Inequalities" by Marek Kuczma, edited by Attila Gilányi, is a comprehensive monograph on functional equations and inequalities. The first edition was published in 1985 and has since become a seminal reference in the field. This second edition, published in 2009, retains the structure and organization of the first edition while incorporating minor revisions marked by footnotes. The book covers a wide range of topics, including set theory, topology, measure theory, and algebra, with a focus on Cauchy's functional equation and Jensen's inequality. It explores the properties of additive and convex functions, inequalities, boundedness, continuity, and related topics such as derivations and automorphisms. The book is intended for mathematicians and researchers interested in functional equations and inequalities, providing a systematic exposition of the theory and numerous exercises for further study.The book "An Introduction to the Theory of Functional Equations and Inequalities" by Marek Kuczma, edited by Attila Gilányi, is a comprehensive monograph on functional equations and inequalities. The first edition was published in 1985 and has since become a seminal reference in the field. This second edition, published in 2009, retains the structure and organization of the first edition while incorporating minor revisions marked by footnotes. The book covers a wide range of topics, including set theory, topology, measure theory, and algebra, with a focus on Cauchy's functional equation and Jensen's inequality. It explores the properties of additive and convex functions, inequalities, boundedness, continuity, and related topics such as derivations and automorphisms. The book is intended for mathematicians and researchers interested in functional equations and inequalities, providing a systematic exposition of the theory and numerous exercises for further study.