This edited book is a comprehensive compilation highlighting sources of biostimulants, their production, influence on plant growth and development, and regulatory status of plant biostimulants for better understanding and opening new vistas for future research. Biostimulants, the biological formulations are known to meliorate the plants growth and vigour, improve nutritional efficiency along with maintaining their well-being mainly via providing protection against a wide range of infections. Both horticultural as well as agricultural crops involve the utilization of the biostimulants. Fulvic and humic acids, nitrogen-containing compounds, protein hydrolysates, favourable bacteria and fungi, and extracts of seaweed are the chief active components of these. The major driving force for these materials is the organic farming industry and demand for sustainable crop production. This book will be of great interest to researchers, teachers, climate change scientists, capacity builders, and policy makers. Moreover, this book does the work of a supplementary reading for students in various fields such as agriculture, soil science, ecology, environmental science and forestry at undergraduate as well as graduate level. This will be a gainful read for national and international agricultural scientists and the policy makers.