[[Image:Marijuana.jpg|thumb|250px|right|Indoor Marijuana Grow (DEA photo)]]
'''Marijuana''' (colloquially known as "weed" or "pot" or "dope" or "reefer") is the name given to the flowering buds of the ''cannabis sativa'' plant prepared for human consumption. The main psychoactive ingredient in marijuana is [[tetrahydrocannabinol|THC]], or delta-9-tetrahydrocannabinol, an [[organic chemistry|organic chemical]] compound which imitates natural cannabinoids produced in the human body. Because THC is considered harmful, marijuana is generally illegal to possess, cultivate and sell in most countries, although it is legal in a some liberal jurisdictions when prescribed as by a physician.<ref>The sale of marijuana is illegal virtually everywhere in the world, and results in long prison sentences in many places. In Portugal, Argentina, California and South Australia, the use (rather than the sale) of small quantities of marijuana is allowed. In only one country in the world, the Netherlands, the sale of marijuana in small quantities is reportedly allowed by law enforcement.</ref> The crime rate in Denver has skyrocketed by 44% since marijuana was legalized in that state.
In the past two decades, the number of brain tumors has increased by up to 40% in the U.S. and Europe, particularly among men between ages of 20 and 40<ref>http://www.healthandenvironment.org/brain_cancer/peer_reviewed</ref> — the same demographic that is most likely to have smoked pot. However, conclusions based on a review of published biomedical research find that cannabinoid compounds unique to cannabis actually exhibit promising anticancer properties, reducing both tumor size and cancer pain.<ref>{{Cite journal|last=Nikan|first=Marjan|last2=Nabavi|first2=Seyed Mohammad|last3=Manayi|first3=Azadeh|date=2016-02-01|title=Ligands for cannabinoid receptors, promising anticancer agents|url=https://www.ncbi.nlm.nih.gov/pubmed/26764235|journal=Life Sciences|volume=146|pages=124–130|doi=10.1016/j.lfs.2015.12.053|issn=1879-0631|pmid=26764235}}</ref>