Mercaptan is a type of organic compound that contains sulfur. It is characterized by a functional group that includes a sulfur atom bonded to a carbon atom and a hydrogen atom. Mercaptans are often used in the chemical industry and can be found in natural sources, such as natural gas and petroleum. One of the most notable properties of mercaptans is their strong, unpleasant odor, which is often compared to that of rotten eggs. This distinctive smell makes them useful as odorants in natural gas to help detect leaks, as the gas itself is odorless and can be dangerous if inhaled.