Soil horizons are distinct layers of soil that develop over time, each with unique characteristics. These layers are typically classified into three main types: the O horizon, which is rich in organic matter like decomposed leaves; the A horizon, or topsoil, which contains minerals and nutrients essential for plant growth; and the B horizon, or subsoil, which accumulates minerals leached from above layers. Each horizon plays a crucial role in the ecosystem, influencing water retention, root development, and nutrient availability. Understanding soil horizons helps in agriculture, gardening, and environmental conservation, as it informs practices that maintain soil health and productivity.