Having been around for centuries casinos have always offered a range of games of chance to their visitors. However it was not until the late 20th century that casinos began to add luxuries to their facilities like restaurants, free drinks and stage shows. This led to the proliferation of casino locations across the United States. The biggest concentration of them can be found in Las Vegas, with Atlantic City and New Jersey taking a close second and third respectively.
Something about gambling (or the presence of large amounts of money) encourages people to cheat and steal, either in collusion with other patrons or independently. This is a big reason why casinos spend so much time and effort on security measures.
In addition to the physical security measures casinos have in place there are also other ways to prevent theft by their patrons. These methods play on our human tendency to want to satisfy our sense of pleasure through stimulation. This is why casinos use bright lights and the sound of pennies dropping in slot machines even though coins have long since stopped being used. They also employ the use of certain scents that are known to increase play in slots.
As a result of all these factors the house edge for each game gives the casino a virtual guarantee of gross profit. This makes it extremely rare for a player to beat the house and win more than they have spent. Because of this many casinos offer players comps such as free meals, hotel rooms, show tickets and limo service based on the amount they spend at the tables or slot machines.