The Random Number Generator was first used in the electronic slot machine in 1975. One random number was used for each reel in the machine and the random number was constrained to the number of slots in each reel. Each random number corresponded to a symbol and therefore the sequence of five random numbers corresponded to a line of five symbols. Initially the electronic slots were not popular because the players were sceptical of a technology they could not see. They felt that casinos could rig the machine.
This was one of the reasons that the application of the Random Number Generator to other gambling applications like roulette, blackjack and poker was delayed by almost twenty years. Another reason was that the evolution of Internet technology and the financial and legal frameworks took time. But by the mid 1900s the advantages of the Random Number Generator games could not be ignored and online casinos proliferated.
The major advantage was the saving in time. The spinning of the roulette wheel, the throwing of the dice and the dealing of cards all takes time. However random numbers are generated instantaneously on a computer. Therefore games have become much faster. Also traditional limits to the "size" of the games have vanished. In electromechanical slots the number of slots to a reel was limited by the physical size of the reel. However it is as easy to generate a random number between 1 and 10 as it is to generate a random number between 1 and 100. Hence electronic slots had 25 and more slots to a reel. Similarly players could play blackjack on two or three or more tables simultaneously because the Random Number Generator can generate several sets of random numbers simultaneously.
Today the issue of fairness has also been taken care of. Independent testing agencies evaluate the Random Number Generators used by online casinos and certify them for fairness. They conducted tests over thousands of trials, giving players the assurance that they are not being shortchanged.