The first slot machine came into being in 1895. Since then, they have witnessed not much of evolution. While early slot machines contained three spinning wheels with a symbol, one of them being the jackpot figure, in modern machines the number of reels has been increased to five. The symbols vary from diamonds, spades, clubs, hearts to fruits. Similarly, while the earlier slot machines had only one row, the present ones have two to three horizontal rows, but only one acts as the pay off. Again, classical model had only one pay line, but today the machine can have as many as fifteen pay lines. The player can decide which one he chooses.

Almost all the slot machines are relatively similar. The one characteristic they differ on is the denomination. Some machines accept a quarter, while others can have five dollars as the acceptable denomination, depending on the intensity of the gambler.

An added attraction some machines today is the