Dimethyltryptamine
Dimethyltryptamine (DMT), also known as N,N-dimethyltryptamine, is a psychedelic tryptamine. It is not to be confused with 5-MeO-DMT and is similar in chemical structure to the neurotransmitter serotonin. DMT is created in small amounts by the human body during normal metabolism by the enzyme tryptamine-N-methyltransferase. Pure DMT at room temperature is a clear or white to yellowish-red crystalline solid. DMT was first chemically synthesized in 1931.
DMT occurs naturally in many species of plants often in conjunction with its close chemical relatives 5-MeO-DMT and bufotenin (5-OH-DMT).  DMT containing plants are commonly used in several South American shamanic practices.  It is usually one of the main active constituents of the drink ayahuasca, however ayahuasca is sometimes brewed without DMT containing plants.  DMT occurs as the primary active alkaloid in several plants including such plants as Mimosa hostilis, Diplopterys cabrerana, and Psychotria viridis.  DMT is found as a minor alkaloid in snuff made from Virola bark resin in which 5-MeO-DMT is the main active alkaloid.  DMT is also found as a minor alkaloid in the beans of Anadenanthera peregrina and Anadenanthera colubrina used to make Yopo and Vilca snuff in which bufotenin is the main active alkaloid.
DMT is generally not active orally unless it is combined with a monoamine oxidase inhibitor (MAOI), such as harmaline. Without an MAOI, the body quickly metabolizes orally-administered DMT, and it therefore has no hallucinogenic effect unless the dose exceeds monoamine oxidase's metabolic capacity (very rare).  Other means of ingestion such as smoking or injecting the drug can produce powerful hallucinations and entheogenic activity for a short time (usually less than half an hour).

# Hallucinogenic properties
The psychotropic effects of DMT were first studied scientifically by the Hungarian chemist and psychologist Dr. Stephen Szara who performed research with volunteers in the mid-1950s. Szara, who later worked for the National Institutes of Health, had turned his attention to DMT after his order for LSD from the Swiss company Sandoz Laboratories was rejected on the grounds that the powerful psychotropic could be dangerous in the hands of a communist country. 
DMT is a powerful psychoactive substance. If DMT is smoked, injected, or orally ingested with an MAOI, it can produce powerful entheogenic experiences including intense visual hallucinations, euphoria, even true hallucinations (perceived extensions of reality).
Smoked: If DMT is smoked, the maximal effects last for a short period of time (5 - 30 minutes dose dependent). The onset after inhalation is very fast (less than 45 seconds) and maximal effects are reached within about a minute. The Business Man's Trip is a common name because of the relatively short duration of vaporized, insufflated, or injected DMT.
Insufflation: When DMT is insufflated (snorted through the nostrils) the duration is markedly increased, and some users report diminished euphoria for increased "spiritual" qualities of effect.
Injection: Injected DMT produces an experience similar to inhalation in duration, intensity, and characteristics.
Oral ingestion: DMT, which is broken down by the digestive enzyme monoamine oxidase, is practically inactive if taken orally, unless combined with a monoamine oxidase inhibitor (MAOI). The traditional South American ayahuasca, or yage, is a tea mixture containing DMT and a MAOI. There are a number of admixtures to this brew, but most commonly it is simply the leaves of Psychotria viridis (containing DMT), and the vine Banisteriopsis caapi (the source of MAOI). Other DMT containing plants, including Diplopterys cabrerana, are sometimes used in ayahuasca in different areas of South America. Two common sources in the western US are Reed canary grass (Phalaris arundinacea) and Harding grass (Phalaris aquatica). In addition, mimosa hostilis or jurema shows evidence of DMT content: the pink layer in the bark of this vine contains a high concentrations of N,N-DMT. These invasive grasses contain low levels of DMT and other alkaloids. Taken orally with an appropriate MAOI, DMT produces a long lasting (over 3 hour), slow, but deep spiritual experience. MAOIs should be used with extreme caution as they can have lethal complications with some prescription drugs, such as SSRI antidepressants, and some over-the-counter drugs.
Induced DMT experiences can include profound time-dilation, visual and audio hallucinations, and other experiences that, by most firsthand accounts, defy verbal or visual description. Some users report intense erotic imagery and sensations and utilize the drug in a ritual sexual context.Professor Alan Watts described the effects of DMT as "Load universe into cannon. Aim at brain. Fire."
In a study conducted from 1990 through 1995, UNM, psychiatrist Rick Strassman found that many volunteers injected with high doses of DMT had experiences with a perceived alien entity. Some of these beings are often described as elves, or "aliens," "guides," or "helpers." Visually some are said to resemble clowns, reptiles, mantises, bees, spiders, cacti, gnomes, and stick figures. At least one subject reported sexual contact with these beings, and some others reported erotic experiences. Usually, the reported entities were experienced as the inhabitants of the mental reality the subjects reported visiting on DMT. 

# Side effects
When DMT is vaporized, the vapor produced is often felt to be very harsh on the lungs. According to a "Dose-response study of N,N-dimethyltryptamine in humans" by Rick Strassman "Dimethyltryptamine dose dependently elevated blood pressure, heart rate, pupil diameter, and rectal temperature, in addition to elevating blood concentrations of beta-endorphin, corticotropin, cortisol, and prolactin. Growth hormone blood levels rose equally in response to all doses of DMT, and melatonin levels were unaffected."

# Chemistry
DMT is a derivative of tryptamine with two additional methyl groups at the amine nitrogen atom. DMT was first extracted from the roots of Mimosa hostilis in 1946 by Brazilian ethnobotanist and chemist Goncalves deLima who named it Nigerine. DMT was first synthesized by British chemist Richard Manske in 1931..  DMT is often synthesized by the Speeter-Anthony synthesis from indole using oxalyl chloride, dimethylamine, and lithium aluminium hydride as reagents. DMT is usually used in its base form, but it is more stable as a salt, e.g. as a fumarate. In contrast to DMT's base, its salts are water-soluble. DMT in solution degrades relatively fast and should be stored protected from air and light in a freezer.   Highly pure DMT crystals, when evaporated out of a solvent and depositing upon glass, often produce small but highly defined white crystalline needles which when viewed under intense light will sparkle, and appear colorless under high magnification.

# Speculations
Several speculative and as yet untested hypotheses suggest that endogenous DMT, produced in the human brain, is involved in certain psychological and neurological states. As DMT is naturally produced in small amounts in the brains and other tissues of humans, and other mammals, some believe it plays a role in promoting the visual effects of natural dreaming, and also near-death experiences and other mystical states. A biochemical mechanism for this was proposed by the medical researcher JC Callaway, who suggested in 1988 that DMT might be connected with visual dream phenomena, where brain DMT levels are periodically elevated to induce visual dreaming and possibly other natural states of mind. 
Dr. Rick Strassman, while conducting DMT research in the 1990s at the University of New Mexico, advanced the theory that a massive release of DMT from the pineal gland prior to death or near death was the cause of the near death experience (NDE) phenomenon. Several of his test subjects reported NDE-like audio or visual hallucinations. His explanation for this was the possible lack of panic involved in the clinical setting and possible dosage differences between those administered and those encountered in actual NDE cases.
Several subjects also reported contact with 'other beings', alien like, insectoid and reptilian in nature, in technological environments where
the subjects were 'probed', 'tested' and sometimes even 'manipulated' by these 'beings' (see Abduction phenomenon).
In the 1950s, the endogenous production of psychoactive agents was considered to be a potential explanation for the hallucinatory symptoms of some psychiatric diseases as the transmethylation hypothesis.. Unfortunately, this hypothesis does not account for the natural presence of endogenous DMT in otherwise normal humans, not to mention rats and other laboratory animals. The proposal by Dr. Callaway was the first to suggest a useful function for the endogenous production of DMT; i.e. to facilitate the visual phenomenon of normal dreaming.
Ethical concerns do not allow for the testing of this hypothesis in humans, as the biological samples must come from the living human brain.
Writers on DMT include Terence McKenna and Jeremy Narby, though most scientists who study psychedelic drugs treat their writings with skepticism. McKenna writes of his experiences with DMT in which he encounters entities he describes as "Self-Transforming Machine Elves".  McKenna believed DMT to be a tool that could be used to enhance communication and allow for communication with other-worldly entities.  Other users report visitation from external intelligences attempting to impart information. These Machine Elf experiences are said to be shared by many DMT users. From a researcher's perspective, perhaps best known is Rick Strassman's DMT: The Spirit Molecule (ISBN 0-89281-927-8); Strassman speculated that DMT is made in the pineal gland, largely because the necessary constituents(see methyltransferases) needed to make DMT are found in the pineal gland. However, no one has looked for DMT in the pineal yet.  It's possible Strassman thought that because DMT falls in the large class of chemicals called Tryptamines, which includes Serotonin, LSD, Melatonin (a hormone the Pineal Gland does produce), and Psilocybin.

# Legal status
DMT is classified in the United States as a Schedule I drug. In December of 2004, the Supreme Court lifted a stay thereby allowing the Brazil-based Uniao do Vegetal (UDV) church to use a decoction containing DMT in their Christmas services that year. This decoction is a "tea" made from boiled leaves and vines, known as hoasca within the UDV, and ayahuasca in different cultures. In Gonzales v. O Centro Espirita Beneficente Uniao do Vegetal, the Supreme Court heard arguments on November 1, 2005 and unanimously ruled in February 2006 that the U.S. federal government must allow the UDV to import and consume the tea for religious ceremonies under the 1993 Religious Freedom Restoration Act. There are no drug tests that would show DMT usage. None of the basic NIDA 5 drug tests or any extended drug test will show a result for DMT. 
DMT is classified in Canada as a Schedule III drug.
DMT, along with most of its plant sources, is classified in France as a stupefiant.
DMT is classified in the United Kingdom as a Class A drug.

# Culture
In Brazil there are a number of religious movements based on the use of Ayahuasca, usually in an animistic context that may be shamanistic, sometimes mixed with Christian imagery.
There are four main branches using DMT-MAOI based sacraments in Brazil:
- Indigenous people - they are the oldest culture in the whole South America to use ayahuasca or analogue brews, such as the ones made from Jurema (Mimosa hostilis).
- Santo Daime (Saint Giveme) and Barquinha (Lil'Boat) - the former was founded by  Raimundo Irineu Serra in the early 30s, as an esoteric Christian religion with shamanic tendencies. The Barquinha cult was derived from this one.
- Uniao do Vegetal (Vegetable's Union) - another Christian ayahuasca religion, with a more Masonic tone. Today it's divided into at least three sects.
- Neo-shamans - there are some shamanic facilitators in Brasil using ayahuasca and analogous brews in their rituals and seances, mainly in the State of Sao Paulo.