Rainforests are typically described as having five main layers, not four:

1. Emergent Layer: The tallest trees, reaching above the canopy and often exposed to wind and sun.

2. Canopy Layer: The dense, leafy layer formed by the crowns of most rainforest trees. This is the most biodiverse layer.

3. Understory Layer: The layer beneath the canopy, with smaller trees and shrubs.

4. Shrub Layer: The layer closest to the forest floor, with even smaller plants and ferns.

5. Forest Floor: The ground level, often dark and humid, with decaying leaves and organic matter.

Let me know if you'd like to know more about each layer!