A slot is a narrow opening into which something else can be fitted, especially a bar or bolt used to fasten a door, window, etc. A slot can also be a position in a group, series, or sequence, and a place occupied by a function, process, or program. The meaning as “a position in a list, or in a timetable” is attested from 1942; that of “a spot on the (semi-circular) copy desk at a newspaper,” the spot occupied by the chief sub-editor, is recorded from 1917.
A casino slot machine, or fruit machine in some countries, is a gambling machine which pays out credits according to a paytable. The player inserts cash or, in ticket-in, ticket-out machines, a paper ticket with a barcode, into the machine and activates it by pulling a lever or button. The reels then spin and stop to rearrange the symbols. Depending on the theme, the symbols may include classic objects such as fruits, bells, and stylized lucky sevens. The winnings are based on the combinations and payout amounts indicated by the paytable.
The appeal of slots can be linked to their ease of use, the speed with which players can determine whether they have won or lost, and the degree to which they provide auditory and visual feedback. The latter feature is particularly important in commercial machines because of the high-fidelity attention-grabbing music and animations that accompany wins. Wins and losses on the same machine, however, are not associated with the same level of feedback, and the timing of wins is unpredictable.