(+)-trans,trans-Abscisic acid (ABA) is a naturally occurring plant hormone, specifically a sesquiterpenoid carboxylic acid. It is a key phytohormone involved in various plant physiological processes, most notably in mediating plant responses to environmental stresses such as drought, salinity, and cold. ABA plays a central role in inducing stomatal closure to reduce water loss, promoting seed dormancy, and inhibiting growth under unfavorable conditions. Its primary industrial application is as a plant growth regulator in agriculture. It is used to enhance crop stress tolerance, improve fruit quality, and regulate plant development. As a high-value biochemical, it is also a crucial reference standard and research tool in plant biology and agricultural sciences for studying stress signaling pathways and hormone interactions. From a chemical perspective, ABA serves as a complex, chiral synthetic building block. Its structure, featuring a cyclohexenone ring, a side chain with conjugated double bonds, and a carboxylic acid group, makes it a valuable intermediate for the synthesis of analogs and probes used in fundamental research to explore structure-activity relationships and develop novel agrochemicals.