Open-Door Policy is a term used in international relations. It means that powerful countries have equal opportunities to trade with colonial or developing countries. When countries agree to observe the Open-Door Policy in an area, they simply agree to permit their merchants and investors to trade freely there.
John Hay, United States secretary of state, started the idea of the Open Door in 1899. At that time, several Western powers had special interests in China. Each power was trying to get all the trading rights for itself. Hay sent notes to the competing powers, asking them to maintain complete equality for all nations that wished to trade with China. The competing powers accepted Hay’s proposal, and they signed treaties agreeing to observe the Open-Door Policy.