The importance of the Open Door Policy, drafted in part by the United States Secretary of State John Hay between 1899 and 1900, was that it proposed an open and free market for all interested nations with regard to trade with China. Its intent was to guarantee an equal footing for China's trading partners without allowing any of them to establish an economic hegemony over that nation's international commerce. The policy's aim was to prevent those nations already established within Asia from barring or limiting access to other nations who wished to begin trade relations with China.
Hay hoped that the Open Door Policy would help to build the U.S. economy while also decreasing the tension between those foreign powers already engaged in the Asian trade market. There were concerns that the established foreign trading powers within China would develop into impenetrable individual spheres of influence, or de facto colonies. Although it did not represent a binding agreement between nations, the Open Door Policy served to outline the specifics of the U.S. foreign policy regarding China.
In addition to John Hay's contribution, consisting primarily of a series of diplomatic communications or "notes" sent to the involved nations, the original formulation of the Open Door Policy came from William Woodville Rockhill. The U.S. had increased its Asian presence with its acquisition of the Philippine Islands after the Spanish-American War, but U.S. business interests felt disadvantaged in their ability to enter the now nearby Asian market. Rockhill, an American scholar-diplomat who later became the U.S. Ambassador to China, was called upon to formulate an approach to the issue that would safeguard the anticipated entry of American businesses into the Chinese trade market.