Treaty Trader and Treaty Investor Visas (E1/E2)

The official definition (9 FAM 41.51):

The Immigration and Nationality Act provides this nonimmigrant visa status for a national of a country with which the United States maintains a treaty of commerce and navigation who is coming to the United States to carry on substantial trade, including trade in services or technology, principally between the United States and the treaty country, or to develop and direct the operations of an enterprise in which the national has invested, or is in the process of investing a substantial amount of capital.