A narrow notch, groove or opening, as in the wing of an airplane or the slit for a coin in a vending machine.
A slot is a compartment or position within a group, series, sequence, etc.: a slot in the wall; a slot in time; a position of employment.
Despite technological changes over the years, slot machines have basically worked the same way. A player pulls a handle to spin a set of reels that hold pictures, and wins or loses according to which ones line up with the pay line (a row of winning or losing symbols that runs down the center of a viewing window).
In newer slot machines, there is an electronic component called a random number generator, which determines the results of each spin. So, even though a machine may have gone long without hitting, it’s not “due” to hit soon.
If you want to have a better chance of winning, pick the machines you like best, but don’t get too greedy or bet more than you can afford to lose. That’s the best way to turn a potentially fun and relaxing activity into something that might make you pull your hair out. Also, don’t envy others’ successes by thinking they must have pushed the button at just the right moment; every combination of symbols is equally likely to be produced at any given moment, so there’s no such thing as a hot or cold machine.