Application of fuzzy logic to control theory became successful and revolutionary. Its applications to data analysis, artificial intelligence and computational intelligence are intensively developed. Using fuzzy theory one can provide exact representation of concepts and relations that are vague. On the theoretical side fuzzy theory is applied to a variety of mathematical fields such as analysis, algebra, topology, graph theory, optimization and many branches of operations research. The aim of this book is to enrich the theoretical development of fuzzy sets and to apply the concepts of fuzzy sets to ideals in different algebraic structures namely semigroups, gamma semigroups and subtraction semigroups. The contents of this book will encourage the learners by providing them the required basic and advanced level concepts necessary in the study of fuzzy algebraic structures. Illustrative examples are given to enhance understanding.