Salvia divinorum in the context of "Salvinorin A"

Psychedelics are a subclass of hallucinogenic drugs whose primary effect is to trigger non-ordinary mental states (known as psychedelic experiences or "trips") and a perceived "expansion of consciousness". Also referred to as classic hallucinogens or serotonergic hallucinogens, the term psychedelic is sometimes used more broadly to include various other types of hallucinogens as well, such as those which are atypical or adjacent to psychedelia like salvia and MDMA, respectively.

Classic psychedelics generally cause specific psychological, visual, and auditory changes, and oftentimes a substantially altered state of consciousness. They have had the largest influence on science and culture, and include mescaline, LSD, psilocybin, and DMT. There are a large number of both naturally occurring and synthetic serotonergic psychedelics.

A psychoactive drug, psychopharmaceutical, mind-altering drug, consciousness-altering drug, psychoactive substance, or psychotropic substance is a chemical substance that alters psychological functioning by modulating central nervous system (CNS) activity. Psychoactive and psychotropic drugs both affect the brain, with psychotropics sometimes referring to psychiatric drugs or high-abuse substances, while “drug” can have negative connotations. Novel psychoactive substances are designer drugs made to mimic illegal ones and bypass laws.

Psychoactive drug use dates back to prehistory for medicinal and consciousness-altering purposes, with evidence of widespread cultural use. Many animals intentionally consume psychoactive substances, and some traditional legends suggest animals first introduced humans to their use. Psychoactive substances are used across cultures for purposes ranging from medicinal and therapeutic treatment of mental disorders and pain, to performance enhancement. Their effects are influenced by the drug itself, the environment, and individual factors. Psychoactive drugs are categorized by their pharmacological effects into types such as anxiolytics (reduce anxiety), empathogen–entactogens (enhance empathy), stimulants (increase CNS activity), depressants (decrease CNS activity), and hallucinogens (alter perception and emotions). Psychoactive drugs are administered through various routes—including oral ingestion, injection, rectal use, and inhalation—with the method and efficiency differing by drug.

The terpenoids, also known as isoprenoids, are a class of naturally occurring organic chemicals derived from the 5-carbon compound isoprene and its derivatives called terpenes, diterpenes, etc. While sometimes used interchangeably with "terpenes", terpenoids contain additional functional groups, usually containing oxygen. When combined with the hydrocarbon terpenes, terpenoids comprise about 80,000 compounds. They are the largest class of plant secondary metabolites, representing about 60% of known natural products. Many terpenoids have substantial pharmacological bioactivity and are therefore of interest to medicinal chemists.

Plant terpenoids are used for their aromatic qualities and play a role in traditional herbal remedies. Terpenoids contribute to the scent of eucalyptus, the flavors of cinnamon, cloves, and ginger, the yellow color in sunflowers, and the red color in tomatoes. Well-known terpenoids include citral, menthol, camphor, salvinorin A in the plant Salvia divinorum, ginkgolide and bilobalide found in Ginkgo biloba and the cannabinoids found in cannabis. The provitamin beta carotene is a terpene derivative called a carotenoid.

A head shop is a store that sells drug-related paraphernalia. They emerged from the hippie counterculture in the late 1960s, and at that time, many of them had close ties to the anti-Vietnam War movement as well as groups in the marijuana legalization movement like LeMar, Amorphia, and the National Organization for the Reform of Marijuana Laws.

Products sold may include magazines (e.g., about cannabis culture, cannabis cultivation, tattooing, and music), clothing, and home décor (e.g., posters and wall hangings illustrating drug culture themes such as cannabis, jam bands like The Grateful Dead, Phish, psychedelic art, etc.). Some head shops also sell oddities, such as antique walking sticks and sex toys. Since the 1980s, some head shops have sold clothing related to the heavy metal or punk subculture, such as band T-shirts and cloth patches with band logos, studded wristbands, bullet belts, and leather boots. Other items offered typically include hashish pipes, "one hitter" pipes; pipe screens; bongs (also referred to as water pipes); roach clips (used for smoking the end of a marijuana "joint"); vaporizers used for inhaling THC vapor from cannabis; rolling papers; rolling machines; small weighing scales; small ziplock baggies; cannabis grinders (i.e. herb grinders); blacklight-responsive posters and blacklights; incense; cigarette lighters; "stashes", which include a range of standard consumer products such as clocks, books, tins of cleaning powder, and toilet brushes which have hidden compartments for cannabis and non-camouflaged "stash boxes" which are tins or wooden containers for storing marijuana; and legal highs such as whipped-cream chargers (which contain nitrous oxide) and Salvia divinorum (both of which are illegal in some countries and some US states for recreational purposes). Some head shops also sell items used for home cultivation of marijuana plants, such as hydroponic equipment and lights and guidebooks on cultivation. Since the 2000s, some head shops also sell e-cigarettes and the flavoured liquids used with these devices.