A slot is a narrow aperture or groove, especially one designed for receiving something, such as a coin. Also: (informal) An opportunity or time for something to happen, such as a meeting, an appointment, or a task; a place or position. He dropped the coin in the slot and dialled the phone number.
Historically, all slot machines used revolving mechanical reels to display and determine results. A problem with this system is that the number of combinations is only cubic – an original machine with three physical reels fitted with 10 symbols each had only 103 = 1,000 possible combinations. This limited jackpot sizes and skewed the odds of winning. Modern slot machines use electronics and a computer program to weight particular symbols, allowing a single symbol to appear on multiple reels and thus increasing the probability of a win.
Casino managers are concerned that if they increase the house advantage on a slot too much, players will detect it and choose another casino. Hence the need to add flavor and excitement to the games in order to keep the players interested. This is why you’ll see special winning scenes on the LCD display and energizing music playing when you hit a jackpot.