Operation Web Tryp was a United States Drug Enforcement Administration operation that ended on July 21, 2004 with the arrests of 10 persons. Its purpose was to investigate web sites suspected of distribution of unscheduled, unregulated tryptamines and phenethylamines of questionable legality. This trade in "grey market" drugs, which were not explicitly illegal but potentially prosecutable as drug analogs, became known as the "research chemical" trade; a euphemism to suggest that the chemicals were being sold for industrial or academic research rather than human consumption.