Short answers, pulled from the story.
The Italian Communist Party was founded on the 21st of January 1921 in Livorno. A small group of men gathered to forge this new political entity after refusing to expel reformist members from the Italian Socialist Party.
Amadeo Bordiga emerged as the secretary of the party while Antonio Gramsci and Nicola Bombacci led other factions within the assembly. The organization adopted a program based on Lenin's vision for the Russian Communist Party that outlined ten points including the catastrophic nature of capitalism and the final call for the extinction of the state.
Fascist authorities outlawed the party during the regime of Benito Mussolini and more than three quarters of all political prisoners between 1926 and 1943 were communists. The organization maintained a clandestine network despite systematic repression by distributing propaganda leaflets and newspapers while infiltrating fascist unions.
The party returned to legal status after the fall of Fascism on the 25th of July 1943 and took part in every government from June 1944 to May 1947. Bologna served as the municipal showcase for the Italian Communist Party from 1945 onwards where local administrations tackled urban problems with successful programs for health care and education.
On the 31st of May 1947 the United States engineered the expulsion of all left-wing ministers from the cabinet because Ambassador James Clement Dunn directly asked de Gasperi to dissolve parliament and remove the PCI. George Marshall informed De Gasperi that anti-communism was required for American aid and the United States spent ten to twenty million dollars on covert operations against communist groups.
Achille Occhetto became general secretary of the Italian Communist Party in 1988 and announced its dissolution at a conference in Bologna that year. Under his leadership the party dissolved and refounded itself as the Democratic Party of the Left while one third of the membership seceded to form the Communist Refoundation Party instead.