Furans are a class of organic compounds characterized by a five-membered aromatic ring containing four carbon atoms and one oxygen atom. They are typically colorless liquids with a sweet odor and are used in various industrial applications, including the production of resins and pharmaceuticals. Furans can be derived from natural sources, such as the thermal degradation of carbohydrates. These compounds are also significant in environmental chemistry, as they can form during the combustion of organic materials. Some furans, like furan-2-carboxylic acid, are studied for their potential health effects, as they can be toxic and carcinogenic in certain conditions.