This is an educational guide to how UK online gambling works. Figures are typical industry values and vary by operator. Play for entertainment, never as a way to make money, and only ever stake what you can afford to lose.
What Is an RNG in Gambling?
An RNG — random number generator — is the software at the heart of every fair online casino game. It decides outcomes randomly, so no one (including the casino) can predict or control them. Here's how it underpins fair play.
What it does
Every spin, deal or draw is determined by the RNG producing an unpredictable result, independent of what came before. The game has no memory — a previous outcome never influences the next, which is why "due" wins are a myth.
How fairness is proven
Licensed RNGs are tested by independent laboratories to confirm they're genuinely random and that published return-to-player figures are accurate. In the UK, this testing is part of being licensed.
Can it be rigged?
On a UK-licensed site, no — the maths is built and tested by the game maker, and the operator can't secretly alter it. For more, see whether online slots are rigged, what RTP means and what a UKGC licence means.
Frequently asked questions
What is an RNG?
A random number generator — software that produces unpredictable, independent outcomes for games.
Is it really random?
Licensed RNGs are independently tested to confirm they are.
Can the casino control it?
No — on licensed sites the outcomes can't be manipulated by the operator.
Related guides: whether online slots are rigged, what RTP means and what a UKGC licence means.