This book "Introduction to Set Theory" is A very important in the field of modern algebru. It is very important to Study this hook to study modern mathematics. This book contain preliminary Notation, Sets, Subsets, Mapping Function and Relation. This book is useful to the students of under graduate, post graduate students and the candidate appearing in various competitions like pre Engineering/I.A.S./P.C.S. etc. Contents, Preface 1. PRELIMINARY NOTATION : Introduction, Statements, Set, How to Describe or Specify a Set, Sets of Numbers, Empty Set, Finite and Infinite Sets, Equal Sets, Equivalent Sets, Subsets, Some Results on Subsets, Universal Set, Operation on Sets, Complement of a Set, Some Results on Complementation, Law of Operations, Some Other Results on Operations on Sets, Ordered Pair, Cartesian Product or Direct Product of Sets, Some Results on Cartesian Product of Sets, Relations, Inverse Relation, Composite Relation, Binary Relation, Various Types of Relations on a Set, Equivalence Classes, Binary Operation or Binary Composition on a Set, Laws of Binary Composition, Composition Tables for Binary Compositions on Finite Sets.