Smoking is a habit where burns are burned and smoke is released to taste and enter the bloodstream. Most commonly, the substance used is the dried leaves of a tobacco plant, wrapped in a small square of rice paper to form a small circular cylinder called "tobacco". Smoking is mainly done as a way of treating recreational drug use because the combination of a dried plant leaves energy and releases active substances into the lungs when they are quickly absorbed into the bloodstream and reach the body's tissues. In the case of cigarette smoking these substances are contained in a portion of aerosol particles and gases and include the alkaloid nicotine active in the pharmacy; vaporization creates aerosol and warm gas into a conduit that allows breathing and deep penetration into the lungs where it absorbs into the bloodstream of the active substance. In some cultures, smoking is also performed as part of various rituals, where participants use it to help convey such passions as, they believe, can lead to spiritual enlightenment.