Slot machines have been around since the late 1800s. Originally they had only three reels with a small number of symbols. The rarest symbol was a Liberty Bell, giving the machine its name. The machine was popular with bars, cigar stores, bowling alleys, and many other locations. In the early years demand was higher than production.
 
As other individuals and companies entered the industry many challenges were overcome. The difficulties of mechanically paying out on five reels with poker style symbols was one of the first. To avoid laws against gambling many machines paid out gum or tokens that could be exchanged at the establishment for drinks, cigars, or other prizes.

In the decades since many improvements and adjustments have been made to increase the enjoyment of the players. Mechanical reels were later computer controlled. This allowed manufacturers to “weight” stops on the reels causing the symbol to appear more often without placing more copies of the same symbol on the reels. Hoppers to contain coins were added to eliminate the constant need for an attendant to handle payouts. Inserted coins would fall into the hopper to replenish coins distributed to the player.

Advances in computer technology and video graphics gave slot machines and similar games a boost in options and control for gaming companies and regulatory agencies. Microchips than can generate vast numbers of random numbers are now used in the place of mechanical devices that could easily be tampered with. Push buttons and touch screens have made the traditional pull arm on the side of modern slot machines a decorative piece.

Manufacturers like Bally Gaming and website like Vera John Slots can now make games with a wide variety of themes. Movies, the Old West, and the ocean depths are all possible themes for those making slot style games.