This book is intended for post-graduate-level students of Organic chemistry which will serve as a supplement for Heterocyclic Chemistry textbook. It can also be used as a stand-alone text book for post graduate levels for all Indian institutes. This book is written in the form of a lecture series for easy comprehension. Synthesis, mechanism, electrophilic and nucleophilic aromatic substitution reactions of 1,2 & 1,3- Azoles are provided in this book. I hope this book will be very helpful to the students for all competitive exams related to Chemistry like IIT-JAM, CSIR-UGC (NET/JRF), GATE, SET, TIFR, ONGC, BARC, IISc, DRDO, etc.