In world war 1 the central powers were Germany, Austria-Hungary and the Ottoman empire. The allies where The British empire, France, Russia and later the United states.
Italy was a member of the Tripl Alliance, which formed into the main nations of the Central Powers when war broke out. It joined the war on the Allied Side.
Related topics:
Central Powers
(war, organization, Germany/Austro-Hungaria/Bulgaria - in history)