Ether is a colorless, volatile liquid that was historically used as an anesthetic in medicine. It is a type of organic compound known as an ether, which contains an oxygen atom connected to two alkyl or aryl groups. Ether was commonly used in surgeries to induce unconsciousness before the development of modern anesthetics. In addition to its medical uses, ether is also a solvent in laboratories and industries. It can dissolve a variety of organic compounds, making it useful for chemical reactions and extractions. The term "ether" can also refer to the hypothetical medium once thought to fill space and transmit light waves, known as luminiferous ether.