A conventional good online slot gambling site machine was a mechanical device that had several spinning reels. These were usually powered by a lever on the side of the equipment. The reels had various designs or pictures painted on them. The reels spun around when the lever was pulled and if the right combination came up the player was a winner. The lever gave rise to the popular American slang term: one armed bandit.

These machines were the first coin operated gaming devices marketed and also are still among the most popular. Most casinos now feature large banks of them as well as the gaming industry now derives most of its revenue from devices for example fruit machines.

In certain places; for example most of the US and Canada, these machines are limited to licensed casinos as well as other gambling halls. In other areas such devices might be found in almost any public place including bars, pubs, amusement arcades and bookmakers shops.