How did the triple alliance became the central powers?

The Triple Alliance, originally consisting of Germany, Austria-Hungary, and Italy, transformed into the Central Powers during World War I when Italy opted to join the Allies instead of supporting its former allies. Germany and Austria-Hungary remained united, and they were soon joined by the Ottoman Empire and Bulgaria, who aligned with them against the Allies. This coalition of nations became known as the Central Powers as they fought primarily in central Europe against the Allied Powers. The alliance was characterized by military cooperation and shared goals in the conflict.