According to Bloomberg, accumulated revenue of the biggest casino operator companies worldwide amounted to almost US$55\u00a0billion in 2011. The term casino may mean a small country villa, summerhouse, or social club. The casino industry is a major part of the tourism and leisure industry, with the largest casino operator companies generating tens of billions of dollars in revenue annually. Some of the most famous casinos in the world include the Monte Carlo Casino, The Venetian Macao, and Caesars Palace. The design of a casino, including factors like sound, odour, and lighting, is often carefully controlled to encourage gambling.<\/p>\n