RNG stands for random number generator, the software that decides the outcome of every digital casino game, from slot spins to card shuffles. Casino RNGs are usually pseudo-random: an algorithm produces long sequences of numbers that are unpredictable and statistically random, even though they come from a mathematical process. True random number generators instead sample physical noise, such as electronic or atmospheric signals.
In regulated markets, an RNG cannot simply be taken on trust; it must be tested by an accredited laboratory, which checks that results are unpredictable, evenly distributed and correctly mapped to game outcomes. Many regulators also require ongoing monitoring of return to player figures. For operators, working with certified games and keeping their certificates on file is part of licence compliance, and it is a key point to confirm when adding content through a games integration. Compare provably fair games.