Charles Ponzi was an Italian con artist who became infamous for his fraudulent investment scheme in the early 20th century. He promised investors high returns on investments in international postal reply coupons, claiming he could buy them cheaply in countries with lower currency values and sell them at a profit in the United States. The scheme relied on new investors' money to pay returns to earlier investors, creating a cycle of deception. This type of scam is now known as a Ponzi scheme. Ponzi's operation collapsed in 1920, leading to his arrest and highlighting the dangers of such fraudulent schemes.