Cannabis, also known as marijuana (from the Mexican Spanish marihuana) and by other names, refers to preparations of the Cannabis plant intended for use as a psychoactive drug and as medicine. Chemically, the major psychoactive compound in cannabis is delta-9-tetrahydrocannabinol (Δ9-THC); it is one of 400 compounds in the plant, including other cannabinoids, such as cannabidiol (CBD), cannabinol (CBN), and tetrahydrocannabivarin (THCV), which can produce sensory effects unlike the psychoactive effects of THC.
Contemporary uses of cannabis are as a recreational drug, as religious or spiritual rites, or as medicine; the earliest recorded uses date from the 3rd millennium BC. In 2004, the United Nations estimated that global consumption of cannabis indicated that approximately 4.0 percent of the adult world population (162 million people) used cannabis annually, and that approximately 0.6 percent (22.5 million) of people used cannabis daily. Since the early 20th century cannabis has been subject to legal restrictions with the possession, use, and sale of cannabis preparations containing psychoactive cannabinoids currently illegal in most countries of the world; the United Nations has said that cannabis is the most used illicit drug in the world.
The legality of cannabis concerns laws which in most countries regulate the, use, possession, cultivation, transfer, and trade in Cannabis. Since the beginning of widespread cannabis prohibition around the mid 20th century, most countries have not re-legalized it for personal use, although more than 10 countries tolerate (or have decriminalized) its use and/or its cultivation in limited quantities. Medicinal use of cannabis is also legal in a number of countries, including Canada, the Czech Republic, Israel and 16 states of the United States. In the Netherlands cannabis is formally illegal, but Justice-guidelines show that no action is to be taken in case of possession of a small amount and sale under strict conditions.