Humic substances are organic compounds found in soil, sediment, and water, formed from the decomposition of plant and animal matter. They play a crucial role in soil health by improving nutrient availability, enhancing water retention, and promoting microbial activity. These substances are typically categorized into three main types: humic acid, fulvic acid, and humin. Each type varies in solubility and molecular weight, contributing differently to soil structure and fertility. Humic substances are essential for sustainable agriculture and environmental management, as they help maintain ecosystem balance.