Provably fair is a method for proving that a result was decided before you played, not adjusted afterwards. It answers one specific suspicion — and only that one.
How it works
Before the round the operator generates a server seed and shows you its hash. You supply
or accept a client seed. The two, plus a counter, produce the round result. Afterwards the
server seed is revealed, and you can recompute the hash and the result yourself. If the hash
matches the one shown before the round, the server could not have changed the outcome after
seeing your bet.
Verifying a round
Copy the hashed server seed shown before you play.
Play the round.
Reveal the server seed in the game's fairness panel.
Hash the revealed seed and compare it with the one from step one.
Feed both seeds and the counter into the published algorithm and check the result matches.
Most operators provide a verification page that does the arithmetic. Independent
calculators exist for the common algorithms.
What it proves
That the specific round was not manipulated after your bet was placed. Nothing more.
What it does not prove
That the game is a good bet. A provably fair game with 90% RTP is provably a bad
deal.
That the payout table is generous. Fairness of process says nothing about the terms.
That the operator will pay you. Verification covers the round, not the withdrawal.
The practical value. Provably fair rules out one narrow form of
cheating. Licensing, payout history and published RTP cover the rest, and they matter more.