A Poison is a substance that can cause harm or death when ingested, inhaled, or absorbed through the skin. CYANIDE is a type of poison that is composed of carbon and nitrogen molecules. It is highly toxic and can be fatal in small doses. CYANIDE interferes with the body's ability to use oxygen, leading to asphyxiation and death. It is commonly used in chemical warfare and has been used in several high-profile assassinations.