Isoprenoid biosynthesis is the process by which living organisms produce isoprenoids, a diverse class of organic compounds. These compounds are essential for various biological functions, including cell membrane structure, signaling, and the synthesis of hormones. The biosynthesis occurs through two main pathways: the mevalonate pathway and the methylerythritol phosphate (MEP) pathway, which convert simple precursors into isoprenoid units. The isoprenoid units, known as isoprene units, are five-carbon molecules that can be linked together to form larger structures. These larger isoprenoids include terpenes, sterols, and carotenoids, which play crucial roles in plant and animal physiology. Understanding isoprenoid biosynthesis is important for applications in medicine, agriculture, and biotechnology.