There are many different names for marijuana. Slang terms for drugs change quickly, and they vary from one part of the country to another. They may even differ across sections of a large city.

Terms from years ago, such as pot, herb, grass, weed, Mary Jane, and reefer, are still used. You might also hear the names Aunt Mary, skunk, boom, gangster, kif, or ganja.

There are also street names for different strains or "brands" of marijuana, such as "Texas tea," "Maui wowie," and "Chronic." One book of American slang lists more than 200 terms for various kinds of marijuana.

Marijuana is a green, brown, or gray mixture of dried, shredded leaves, stems, seeds, and flowers of the hemp plant (Cannabis sativa). Before the 1960s, many Americans had never heard of marijuana, but today marijuana is the most often used illegal drug in this country.

Cannabis is a term that refers to marijuana and other drugs made from the same plant (Cannabis sativa). Strong forms of cannabis include sinse-milla (sin-seh-me-yah), hashish ("hash" for short), and hash oil.

All forms of cannabis are mind-altering (psychoactive) drugs; they all contain THC (delta-9-tetrahydrocannabinol), the main active chemical in marijuana. They also contain more than 400 other chemicals.

Marijuana's effect on the user depends on the strength or potency of the THC it contains. Marijuana's THC potency has increased since the 1970s and continues to increase still. The strength of the drug is measured by the average amount of THC in test samples confiscated by law enforcement agencies.

• Most ordinary marijuana contained, on average, 5 percent THC.
• Sinsemilla (made from just the buds and flowering tops of female Cannabis sativa plants) contained, on average, 12 percent THC, ranging up to 27 percent.
• Hashish (the sticky resin from the female Cannabis sativa plant flowers) had an average of 10 percent, ranging up to 26 percent.