Cannabis smoking is the inhalation of smoke or vapors released by heating the flowers, leaves, or extracts of cannabis. Smoking releases the main psychoactive chemical in cannabis, Δ⁹-tetrahydrocannabinol, which is absorbed into the bloodstream via the lungs. Apart from being smoked and vaporized, cannabis may be consumed orally or applied to the skin; the bioavailability characteristics and effects of smoking and vaporizing cannabis differ from other consumption methods in having a more rapid and predictable onset of effect.