Gambling probably predates recorded history, with primitive protodice and carved six-sided dice found in archaeological sites. But casino as an institution, a place where people could find a variety of ways to gamble under one roof, did not develop until the 16th century, with a gambling craze sweeping Europe at the time.
The basic idea is that casinos earn money from the odds built into games like poker, blackjack and roulette, which have a statistical advantage for the house (lower than two percent) based on millions of bets made by players over decades. This money allows the casino to build elaborate fountains, towers and replicas of famous landmarks. In addition, casinos earn from the vig or rake, which is a percentage of each bet.
Casinos also earn a significant proportion of their profits from slot machines, which are the least skill-intensive games. A player simply puts in some cash, pulls a handle or pushes a button and watches varying bands of colored shapes roll past on reels (actual physical reels or a video representation of them). If the right pattern appears, the player wins a predetermined amount of money.
Casinos employ many security measures to keep their patrons safe. These include trained security personnel, random audits of player cards and high-tech systems that allow employees to watch every table, window and doorway from a control room filled with banks of monitors. Because of the large amounts of currency handled within a casino, both patrons and staff may be tempted to cheat or steal, in collusion with each other or on their own. In response, most casinos have extensive security measures, including cameras that can be adjusted to focus on suspicious patrons.