A slot is an opening or hole, especially one into which something can be inserted, such as a coin. A slot on a computer is a place in the system into which data can be stored. A slot in a schedule is an open time period when an activity can take place. You can book a slot for an activity online or over the phone.
A video slot machine is a casino game that uses a video screen instead of reels and is controlled by a central computer system. Several studies suggest that the visual and audio stimuli associated with winning on a slot machine acquire conditionally reinforcing properties, encouraging gambling behaviour.
In the past, slot machines were all-or-nothing affairs: you yanked the lever and either all the cherries or lucky sevens lined up and paid out, or they didn’t. By the 2000s, better computer technology enabled casinos to control the odds of each spin and offer higher jackpots with more exciting games. The new technology also allowed them to make the machines more appealing to players by adding lights, sounds, a hopper for coins and the option to bet more than one coin.
Modern multiline video slots often have as many as 200 possible “lines” of symbols, up and down, diagonals, or whatever the manufacturer wants to display. Each line has a different probability of winning, but the total is the same long term. The computer in the slot machine knows this and is able to show winning lines with animations and energizing music, but it can also pause or disable these features if there are no wins.