WHAT IS MARIJUANA?
Marijuana is the word used to describe the dried flowers, seeds and leaves of the Indian hemp plant. On the street, it is called by many other names, such as: astro turf, bhang, dagga, dope, ganja, grass, hemp, home grown, J, Mary Jane, pot, reefer, roach, Texas tea and weed.
Hashish is a related form of the drug, made from the resins of the Indian hemp plant. Also called chocolate, hash or shit, it is on average six times stronger than marijuana.
Cannabis describes any of the different drugs that come from Indian hemp, including marijuana and hashish.
Regardless of the name, this drug is a hallucinogen a substance which distorts how the mind perceives the world you live in.
The chemical in cannabis that creates this distortion is known as THC. The amount of THC found in any given batch of marijuana may vary substantially, but overall, the percentage of THC has increased in recent years.
HOW IS IT USED?
Marijuana is the most commonly used illegal drug in the world. A survey conducted in 2007 found that 14.4 million individuals in the US alone had smoked marijuana at least once during the previous month.
Marijuana is usually smoked as a cigarette (joint), but may also be smoked in a pipe. Less often, it is mixed with food and eaten or brewed as tea. Sometimes users open up cigars and remove the tobacco, replacing it with pot—called a blunt. Joints and blunts are sometimes laced with other, more powerful drugs, such as crack cocaine or PCP (phencyclidine, a powerful hallucinogen).
When a person smokes a joint, he usually feels its effect within minutes. The immediate sensations—increased heart rate, lessened coordination and balance, and a dreamy, unreal state of mind—peak within the first 30 minutes. These short-term effects usually wear off in two to three hours, but they could last longer, depending on how much the user takes, the potency of THC and the presence of other drugs added into the mix.
As the typical user inhales more smoke and holds it longer than he would with a cigarette, a joint creates a severe impact on one’s lungs. Aside from the discomfort that goes with sore throats and chest colds, it has been found that consuming one joint gives as much exposure to cancer-producing chemicals as smoking five cigarettes.
The mental consequences of marijuana use are equally severe. Marijuana smokers have poorer memories and mental aptitude than do non-users.
Animals given marijuana by researchers have even suffered structural damage to the brain.
Source : http://www.drugfreeworld.org/drugfacts/marijuana.html