Methylenedioxymethamphetamine (commonly abbreviated MDMA), which is widely referred to as Ecstasy, is a psychoactive drug that is illegal in the United States. It is considered to be an empathogenic-enactogen. It is usually taken in pill form, though it is increasingly common for it to be sold in its pure crystalline form.
The drug first achieved wide-spread popularity when a former seminary student, Michael Clegg, residing in Texas, was inspired by his first experience with the drug. He claimed that he had always wanted to know "the thoughts of God". At a time when the substance was unscheduled and unregulated, he began giving the drug away for free, but started selling it when the cost of production became "prohibitively expensive". 
Recently, the Multidisciplinary Association for Psychedelic Studies (MAPS) has received FDA-approval for research into the possible benefits of MDMA in the treatment of post-traumatic stress disorder. The results thus far have been uniquely promising. 
Effects of MDMA
MDMA produces a euphoric "high" that lasts several hours by releasing serotonin, dopamine, and oxytocin amongst other neurotransmitters. Users become extraordinarily peaceful and friendly as almost all hostility is repressed as long as the drug is unadultered with other substances such as amphetamine. Appreciation of music and texture is heightened and is often used by people in clubs and at raves. A short period of diminished mood and a general feeling of malaise are a common once the high diminishes, although many users report little or no negative after-effects.
At high doses, MDMA may elevate heart rate and blood pressure significantly, cause dehydration, and hyperthermia. When used repeatedly on the order of several times a month, depression, persistent anxiety, and short-term memory loss may result. Whether or not these effects are reversible remains an area of ongoing research. There is enough evidence to suggest that long term use of ecstasy at high doses can cause nerve damage in a number of users. Taking ecstasy during pregnancy can increase the risk of congenital abnormalities by a factor of 8.