Cyclopentadiene is a colorless, flammable liquid with a distinctive odor. It has the chemical formula C5H6 and consists of a five-membered carbon ring with two double bonds. This structure makes it a diene, which is a type of hydrocarbon that contains two double bonds. Cyclopentadiene is commonly used in organic synthesis and as a building block for various chemical compounds. It can be polymerized to form polycyclopentadiene, a material used in the production of resins and plastics. Additionally, it serves as a precursor for the synthesis of fulvenes and other important organic molecules.