Great Britain, France, the United States and Russia made up the Allies that were victorious in World War I. The opposing forces of Germany and Austria-Hungary were referred to as the Central Powers. Italy had joined the triple alliance, but stepped back when Austria-Hungary broke the terms of the alliance.
The Allies for the majority of the war were without America's assistance. It wasn't until 1917 that the U.S. officially entered the war to help uphold democracy. America had stayed out before then partially due to the immigrant population asking for the country to stay neutral. The sinking of several U.S. ships and deaths of American citizens finally pushed the nation into joining the Allies.