Based on the classroom lectures, this textbook is primarily designed for the senior undergraduate/graduate students of Mathematics. The book covers the senior undergraduate mathematics course, meeting the curriculum requirements of most universities. Different concepts have been explained in a very lucid language with the help of solved examples that would help the students to understand the subject matter without further reference. The subject matter has been presented in a somewhat informal manner assuming the language and tone of a classroom lecture putting the readers at ease. This book could be used for self- study as well as for a course text, and so full details of almost all proofs are included along with hundreds of solved problems, to give ample guidance in understanding abstract notions. The solved problems are interspersed throughout the text at places where they naturally arise, making the book ideal for self-study. The proofs are precise and complete, backed up by chapter end problems, with just the right level of difficulty. A common thread runs through the entire book, tying each chapter to the next - the unifying thread being the treatment of the concept of symmetry of objects that do indeed satisfy the definition of a group. Contents: 1. Groups 2. Finite Groups and Subgroups 3. Cyclic Groups 4. Permutation Groups 5. Cosets and Lagrange’s Theorem 6. Normal Subgroups and Factor Groups 7. Group Homomorphism and Isomorphism 8. Automorphisms 9. Direct Products 10. Group Actions 11. Sylow Theorems About the Authors Dr. Dinesh Khattar, an erstwhile Principal (2015 to 2018) is currently a Professor at the Department of Mathematics, Kirori Mal College, University of Delhi. He topped (Gold Medalist) both in his B.Sc and M.Sc exams of Delhi University. He received Dr. S. Radhakrishnan Memorial National Teacher's Award 2015 for his contribution in the field of education. He was also awarded the prestigious Commonwealth Scholarship for pursuing research in UK. He is actively involved in research and has presented papers in prestigious international conferences across the globe. Dr. Khattar has been a member of curriculum development committee for B.Sc. And M.Sc. Programs at various universities including the University of Delhi. He is also an author of many books on Mathematics. Dr. Neha Agrawal, completed her education from Kirori Mal College, University of Delhi and pursued her M.Phil. And Ph.D. from University of Delhi. Her areas of interest are Nonlinear Dynamical Systems and Chaos Theory. She is working as an Assistant Professor at the Department of Mathematics, Kirori Mal College since 2012 and has also taught in other prestigious colleges like Miranda House, Daulat Ram and NSIT. She has a rich teaching experience of over 12 years. She has published several research papers in reputed international journals.