Server Seed vs Client Seed

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What it means​

Server seed vs client seed describes the two secret inputs that sit behind every provably fair game outcome. The server seed is generated and hashed by the operator and kept secret until reveal, while the client seed is supplied or edited by the player. A round counter called a nonce increments with each bet, so the same seed pair can deterministically produce a long series of outcomes.

When a player places a bet, the casino hashes the combined server seed, client seed and nonce to derive a result, such as a crypto dice roll or a card draw. Because only the hash of the server seed is published up front, the operator cannot change the seed after seeing the player input, and the player cannot predict the result in advance. This commit-and-reveal structure is what distinguishes provably fair from a conventional RNG that players cannot inspect directly.
After the operator rotates the seed pair and reveals the raw server seed, the player can recompute every outcome and confirm nothing was tampered with. The two seeds protect against different attacks: the server seed stops the operator from cherry-picking results, while the editable client seed stops the operator from tailoring a seed to a known input.