The concepts of fuzzy sets and interval valued fuzzy sets introduced by Zadeh are very useful tools to describe situations in which the data are imprecise or vague. The use of fuzziness in algebraic structures were initiated by Rosenfeld and he defined fuzzy groups. J. Ahsen initiated the study of fuzzy semirings. Semirings or hemirings are very useful for solving problems in different areas of applied mathematics and information sciences. Ideals of hemirings play an important role in the study of theory of hemirings and are very useful for many purposes. In this book the author has Characterized different classes of hemirings by using their fuzzy and interval valued fuzzy ideals.