What causes sap?

Sap is produced by trees and plants as a response to various physiological processes, primarily for nutrient transport and defense. It carries water, minerals, and sugars from the roots to other parts of the plant. Additionally, sap can flow in response to injury, as it helps seal wounds and deter pests, acting as a protective mechanism. Different types of sap, such as resin, also serve specific functions in plant health and survival.