Cannabis smoking
Cannabis smoking (known colloquially as smoking weed or smoking pot) is the inhalation of smoke or vapor released by heating the flowers, leaves, or extracts of cannabis and releasing the main psychoactive chemical, Δ9-tetrahydrocannabinol (THC), which is absorbed into the bloodstream via the lungs. Archaeological evidence indicates cannabis with high levels of THC was smoked at least 2,500 years ago.