This book discusses the recent developments of green synthesis methods and presents the various application in different field. this text book give brief over view related with various nanoparticle synthesis using bacteria, fungi, algae, and plant extract. This text book also discussed different synthesis conditions and various affecting factors and their effects. Lastly, this book reviewed various applications using green nanoparticles and give brief list about synthesis method and other physical parameters. This text book also discussed toxicity effects and cancer applications. This text book is valuable friendly guide for students, researchers and policymakers easily under stand the green nanotechnology and nanoscience.