Short answers, pulled from the story.
The Italian economic miracle was a prolonged period of strong economic growth in Italy following World War II, lasting into the late 1960s. Historians identify the years from 1958 to 1963 as the most intense phase. Italy's GDP grew at an average of 5.8% per year between 1951 and 1963.
Italy received $1.5 billion in Marshall Plan aid between 1948 and 1952. The United States provided this assistance because Italy was seen as a strategically important ally during the Cold War, sitting between Western Europe and the Mediterranean and facing a strong domestic Communist party.
The boom ended due to a combination of the Hot Autumn strikes and widespread social unrest in 1969-1970, followed by the 1973 oil crisis. Italy's economy never returned to its post-war growth rates after those two shocks converged.
Around 9 million people are estimated to have taken part in inter-regional migrations within Italy between 1955 and 1971. Most moved from rural Southern Italy to the industrial cities of the north, particularly to the triangle formed by Milan, Turin, and Genoa.
In 1955 only 3% of Italian households owned a refrigerator and just 1% owned a washing machine. By 1975 those figures had risen to 94% and 76% respectively, and 66% of all homes had come to possess cars.
Directors Dino Risi, Vittorio De Sica, and Ettore Scola made films that criticised the selfishness and immorality they associated with the boom years. Risi's Il Sorpasso (1962) and I Mostri (1963), De Sica's Il Boom (1963), and Scola's C'eravamo tanto amati (1974) all addressed this theme. Intellectuals Pier Paolo Pasolini and Luciano Bianciardi were also prominent critics.