Book excerpt: The convergence of nanotechnology with agriculture has transformed farming, while also impacting medicine, biotechnology and environmental science. Plant extracts isolated using new technologies have been used to successfully create new medicines for specific diseases. This book focuses on the eco-friendly synthesis of plant extracts. It provides information about multifunctional nanoparticles, and their versatile applications, including agriculture, food safety, and environmental remediation. The book aims to bridge the gap between nanotechnology and public perception, addressing concerns related to health and environmental impact. Themes within the book span across green synthesis techniques for noble metal nanoparticles, the crucial role of analytical methods in characterizing these "green nanomaterials," and the comprehensive examination of how nanoparticles interact with the human body. Furthermore, the intricate relationships between proteins and nanoparticles is highlighted to explain the physicochemical effects and toxicity of nanomaterials. Readers will learn about sustainable and environmentally friendly approaches for synthesizing nanoparticles, while getting a glimpse of the promising future of nanotechnology in agriculture and beyond.