Heterocyclic compounds are organic compounds that contain rings of carbon atoms and at least one atom of another element, such as nitrogen, oxygen, or sulfur. These compounds are widely used in medicinal chemistry, as many biologically active molecules contain heterocyclic structures. Examples of heterocyclic compounds include pyridine, furan, and thiophene. Researchers study heterocyclic compounds to understand their chemical and physical properties, as well as to develop new drugs, agrochemicals, and materials with improved properties.