How did the alliances change once the war stated?

Once World War I began, the alliances shifted significantly as countries mobilized for war. The initial alliances, primarily the Triple Entente (comprising France, Russia, and the United Kingdom) and the Triple Alliance (including Germany, Austria-Hungary, and Italy), were tested. Italy switched sides in 1915, joining the Allies, while other nations, such as the Ottoman Empire and Bulgaria, aligned with the Central Powers. These changes reflected the complex political dynamics and national interests that evolved as the conflict escalated.