Some unique features of this book are: Content has been written in a simple and lucid language. At the beginning of each chapter, sub-topics have been given to provide an overview of the concepts covered. Colourful pictures, hand-made illustrations, well-labelled diagrams and flow charts have been incorporated for clear understanding. Each chapter contains additional information and interesting facts related to the topic to keep the young minds engaged. Key terms and Mind Map have been given at the end of each chapter to facilitate recaptulation in the form of specially designed flow charts and arrow diagrams. For self-evaluation, a varierty of questions have been given at the end of each chapter like MCQs, Fill in the blanks, True/False, Match the following, Assertion and Reasoning questions, Short answer questions and Long answer questions. Higher Order Thinking Skills (HOTS), Research-based activities and projects have been given to initiate inquisitiveness in the students. A few relevant case studies have also been added in each chapter. We wish to express thanks to our families for their constant support and encouragement throughout the preparation of this book.