Smoking is a practice in which a substance is burned and the resulting smoke breathed in to be tasted or inhaled. Most commonly the substance is the dried leaves of the tobacco plant which has been rolled into rice paper into a small, round cylinder called a “cigarette”. This is primarily practiced as a route of administration for what has come to be termed “recreational drug use” because the combustion of the dried plant leaves releases active substances into the body. In the case of cigarette smoking these substances are contained in a mixture of aerosol particles and gasses and include the pharmacologically active alkaloid nicotine; the vaporization creates heated aerosol and gas to form that allows inhalation and deep penetration into the lungs where absorption into the bloodstream of the active substances occurs. In some cultures, smoking is also carried out as a part of various rituals, where participants use it to help induce trance-like states that, they believe, can lead them to “spiritual enlightenment”.