1. Water: Water is the most powerful agent of erosion. It can wear away soil, rock, and other materials over time. Water erosion can occur through several processes, including rainfall, runoff, and flooding.

2. Wind: Wind is another major agent of erosion. It can carry away soil, sand, and other particles, especially in dry areas with little vegetation. Wind erosion can create dunes, sandbars, and other landforms.

3. Ice: Ice can also cause erosion through several processes. Glaciers, for example, can scrape away soil and rock as they move. Ice sheets can also cause the ground to freeze and thaw, which can lead to frost heave and other forms of erosion.

4. Gravity: Gravity is a constant force that pulls sediment downhill. It can cause erosion through processes such as landslides, avalanches, and soil creep.