Answer:
During World War I, alliances were formed between countries to provide military and political support to one another. The two main alliances were the Triple Entente, made up of France, Russia, and the United Kingdom, and the Central Powers, made up of Germany, Austria-Hungary, and the Ottoman Empire. Other countries, such as Italy and the United States, eventually joined the war on the side of the Triple Entente. Alliances played a significant role in determining which countries were on which side during the war and also contributed to the outbreak of the war as the countries felt obligated to defend their allies.