Bio fertilizers use living microorganisms to improve soil fertility and promote plant growth. These microorganisms fix atmospheric nitrogen, solubilize phosphorus, and enhance nutrient cycling in the soil. Bio fertilizers form symbiotic relationships with plants, providing essential nutrients and promoting root growth and development. The use of bio fertilizers promotes sustainable agriculture, improves soil health, and reduces dependence on synthetic chemicals. Overall, the principle of bio fertilizers is to harness the power of beneficial microorganisms to promote healthy soils, healthy plants, and a healthy environment.