Pine sap is a sticky, resinous substance produced by pine trees, primarily for protection against insects and diseases. It is composed of various organic compounds, including terpenes and acids, which give it its characteristic smell and properties. When the tree is injured, it secretes sap to seal the wound and prevent further damage. This natural resin has been used by humans for centuries in various applications, such as making turpentine, a solvent, and rosin, used in music for string instruments. Additionally, pine sap can be used in traditional medicine and as a waterproofing agent in crafts.