They are an organized crime family originating from the Sicilian town of Corleone, and based in New York City.
They became the most powerful crime family in New York City after defeating Salvatore Maranzano during the Olive Oil War in the early 1930s.
It was during this time that Vito's eldest son, Santino "Sonny" Corleone, made his reputation and eventually became a caporegime himself.
In 1945, Don Vito Corleone declines the business proposal put forth by drug baron Virgil "The Turk" Sollozzo, and this nearly destroys the family.
Michael carries out Sonny's plan to murder the other New York City Mafia bosses along with Moe Greene, who stood in the way of the family's business interests in Las Vegas, Salvatore Tessio, who betrayed Michael for Barzini, and Carlo Rizzi, who was involved in the murder of Sonny.
Michael Corleone, having sold their interests in casinos and hotels, invests only in businesses unconnected to the Mafia.
He aligns with aging Sicilian Don Altobello to orchestrate an assassination attempt on Michael during a meeting in Atlantic City, New Jersey.