This book provides a comprehensive introduction to astronomy and astrophysics for undergraduate science and engineering students. The book is written as per UGC CBCS syllabus for Undergraduate Physics students, covering a wide range of topics from basic to advanced level. This book covers all the fundamental concepts of modern astronomy and astrophysics, such as astronomical units, astronomical coordinate systems, different types of telescopes, detectors and their uses, the solar system, stellar spectra, composition of stars, stellar evolution, nucleosynthesis, the Milky Way, and other types of galaxies, nebula and cosmology. The last chapter of this book is dedicated to stargazing and the reader will get a flavor of real life sky hopping from there. This book explains each and every topic with necessary details for better understanding of the subject. The content of this book will reflect the dramatic changes and advancements in astrophysics that have occurred over the last few decades. The materials of this book will help the students to build up their basic knowledge of astronomy and astrophysics.