The part of online gambling that produces the most complaints is not the games. It is the account: verification documents, withdrawal windows, limits applied after a win, bonus terms that void a pay, and the difference between a source-of-funds check and a source-of-wealth check.
These entries follow the money in order — deposit, play, balance, withdrawal, bank — and set out what the operator is allowed to ask for at each step, what it must do within what period, and what the paperwork is for. Most of it exists because of anti-money-laundering law rather than because the casino wants to keep your balance.
Some of it, though, is a term you agreed to. Malfunction clauses, maximum cashouts on bonus wins, dormant-account fees and chargeback consequences are all published, all enforceable, and all easier to read before a withdrawal than during one.
Where a rule differs by jurisdiction — and verification thresholds always do — the entry says so and links to the country page. Nothing here is legal advice; it is what the published rules and terms say.
The single most useful habit is to finish verification before there is a balance worth arguing about. An account asked for documents while a withdrawal is pending is an account with a frozen balance and a queue in front of it; the same documents, sent on the day of registration, are a five-minute formality. Nothing in the paperwork gets easier for having waited, and the operator's obligation to hold the funds until the checks clear does not soften because the delay is inconvenient.
A dispute has an order too, and skipping a step costs weeks. The operator's own complaints procedure comes first, in writing, with the term you are relying on quoted; then the alternative dispute resolution body named in that procedure; then the regulator on the licence. Chargebacks and public pressure look faster and are not — a reversed deposit is treated as a breach of the terms you signed, and it usually closes the account along with the argument.