Barks are the protective outer covering of trees and shrubs. They serve as a barrier against environmental factors such as pests, diseases, and extreme weather. The bark consists of several layers, including the outer bark, which is often rough and textured, and the inner bark, which transports nutrients throughout the plant. Different species of trees have unique bark characteristics, such as color, thickness, and pattern. For example, the bark of a birch tree is known for its white, papery appearance, while the redwood has thick, fibrous bark that can be several feet deep. Understanding bark helps in identifying tree species and assessing their health.