An RNG (random number generator) is the certified software that produces unpredictable game outcomes — every slot spin, card draw and crash-game multiplier starts with a number the RNG generates.

What RNG stands for and what it does

RNG stands for random number generator. In gaming it is the algorithm that decides outcomes: which symbols a slot lands on, which card is dealt next, where the crash-game multiplier busts. The visible animation is only a rendering of a number the RNG already produced.

Modern casino games use cryptographically secure pseudo-random number generators (CSPRNGs) seeded from hardware entropy. "Pseudo-random" means the sequence is generated deterministically from a seed, but with a seed space so large and entropy sources so strong that the output is unpredictable and unrepeatable in practice.

How an RNG is certified

This is why "is the RNG rigged?" has a practical answer: it is rigged toward the house edge by design — that is what RTP means — but the randomness itself is tested and certified. A rigged RNG would fail certification and be illegal to deploy in licensed markets.

The game's math model and RNG implementation are submitted to an accredited testing lab (GLI, BMM, iTech Labs, eCOGRA).
The lab runs billions of generated numbers through statistical suites (frequency, runs, autocorrelation, uniformity tests) to detect any bias or pattern.
The RNG source and seeding process are reviewed for weakness — predictability, replay, state exposure.
The game is certified against the target jurisdiction's technical standards (MGA, UKGC, Curacao, etc.) and the certificate is attached to the game.

RNG vs provably fair vs live dealing

Certified RNG (slots, virtual table games, crash games): outcome decided by the studio's certified RNG on its RGS.
Provably fair (crypto-first games): the outcome is committed with a hash before the round, so the player can verify after the round that nothing changed — often combined with a client seed the player contributed.
Live dealer games: outcomes come from physical cards, wheels and dice on camera rather than an RNG, with the stream and results logged for audit.

What an operator should check before launching games

Which lab certified the games in your catalogue, and for which jurisdictions.
That game outcomes are generated on the studio's RGS, not on any client-side code — client-side "randomness" is not acceptable for real-money play.
That round results are logged with identifiers you can reconcile against your own wallet ledger.
When you integrate through GamingAPI, you inherit each studio's certifications rather than certifying anything yourself — games are launched server-side and every round's bet and win arrives in your ledger with its round ID.