Book excerpt: This book discusses the fundamental concepts of the green synthesis of nanoparticles and presents the latest advances in this emerging field. Providing a comprehensive overview of developments related to nanoparticle synthesis using fungi, algae, bryophytes, pteridophytes, gymnosperms, monocotyledons, dicotyledonous (angiosperms) and animal systems, it also explores techniques for the characterization of these nanoparticles. Lastly, it reviews the applications and toxicity of biologically synthesized green nanoparticles. Given its scope, it is a valuable resource for students, researchers and policymakers working in the field of nanobiotechnology and nanoscience.