Marijuana is the most commonly used illegal drug in U.S. It is also called Cannabis, as it is made up of the parts of Cannabis Sativa hemp plant. Many preparations from the plant are used as psychoactive drug. The main psychoactive chemical compound of the drug is delta9 tetrahydrocannabinol (THC). In addition, marijuana also contains more than 400 other chemicals that induce psychoactive disorders. The resinous form of the drug is called Hashish or hash, which is much stronger than the crude one. Hash contains five to ten times as much as THC. The immediate effects of smoking marijuana include bloodshot eyes, faster heartbeat and pulse rate, and dryness of mouth and throat. The psychic effects of the drug include memory impairment, distorted perceptions, and difficulty in thinking and solving problems. Marijuana also causes damage to human reproductive system, heart and lungs. The drug effects may also result in cancer. According to the data from the National Institute on Drug Abuse, marijuana abuse in the United States reached to more than 28 million Americans, aged 12 and above, that constitute to about 11.3% of the population.