α-Farnesene is a naturally occurring sesquiterpene hydrocarbon found in the skin of apples and other fruits, contributing to their characteristic aroma. It exists as a mixture of isomers, with the (E,E)-form being predominant. This compound plays a role in plant defense mechanisms against pests and pathogens. It is biosynthesized from farnesyl pyrophosphate and is used in the fragrance industry due to its woody, green odor profile. α-Farnesene is also studied for its potential in insect repellents and as a biomarker in food quality assessment. Its structure consists of a 15-carbon chain with four double bonds, making it highly unsaturated and reactive to oxidation.