Online casino basics

How online casinos work

An online casino is a website or app where you play casino games for real money. Most of the games are slots, but you’ll also find roulette, blackjack, baccarat, poker and live dealer games. Every result is decided by a random number generator (RNG), which is tested by independent labs, so no spin or hand can be predicted or influenced.

The first of the online casino basics is simple: the casino always has a built-in edge. Over time, every game pays back slightly less than it takes in. That’s how casinos make money, and it’s why gambling should be treated as paid entertainment rather than a way to earn.

Signing up and verification

To play, you open an account with your name, date of birth and address. UK-licensed casinos must then check that you’re 18 or over and who you say you are before you can deposit or play, even with free spins. Most checks happen automatically in seconds. However, you may sometimes be asked to upload a photo ID or a recent bill.

After that, you choose a deposit method, add funds and pick a game. Because many sites look alike, our UK casino reviews compare the details that matter, such as payout speed, offer terms and the games on offer.

Is it safe? Licensing and the Gambling Commission

Only play at casinos licensed by the Gambling Commission. A UK licence means the casino must keep player funds protected, use fair and tested games, verify customers, advertise responsibly and offer safer gambling tools.

You’ll find the licence number in the casino’s footer. You can then check it on the Gambling Commission public register. In addition, a UK licence gives you access to a free, independent dispute service if a complaint can’t be settled with the casino.

UK rules also protect players in other ways. For example, credit cards have been banned for gambling since April 2020, and slot features that speed up play, such as auto-play and bonus buys, aren’t allowed.

Slots: RTP, volatility and stake limits

Slots are the biggest part of any casino. You choose a stake, spin, and win when matching symbols land on a payline or in a cluster. Modern slots add free spins rounds, wilds, multipliers and jackpots.

RTP (return to player)

RTP is the share of all money staked that a slot pays back over millions of spins. A slot with 96% RTP pays back £96 for every £100 staked on average, so the casino keeps about £4. RTP is a long-run average, though, so your own session can go either way. Most slots sit between 94% and 97%.

Volatility

Volatility describes how wins are spread. Low volatility slots pay small wins often, so your balance moves gently. High volatility slots pay less often, but the wins can be much bigger. As a result, two slots with the same RTP can feel very different to play.

Stake limits

Online slot stakes are capped in Great Britain: £5 per spin if you’re 25 or over, and £2 per spin if you’re 18 to 24. There’s also a minimum spin speed of 2.5 seconds. Want to try a slot first? You can play free online casino games in demo mode with no sign-up.

Table games: roulette, blackjack and baccarat

Table games have fixed rules, so the house edge depends on the game and the bets you choose. These are the online casino basics for the three most popular ones.

Roulette

You bet on where the ball will land on a numbered wheel. European roulette has one green zero, which gives a house edge of 2.7%. American roulette adds a double zero, which almost doubles the edge to 5.26%, so European is the better choice. Learn the bets in our guide to how to play roulette.

Blackjack

You try to beat the dealer’s hand without going over 21. Played with basic strategy, blackjack has one of the lowest house edges in the casino, often around 0.5%. However, look for tables that pay 3 to 2 on a natural blackjack rather than 6 to 5. Our guide to how to play blackjack explains every move.

Baccarat

You bet on the banker hand, the player hand or a tie. There are no decisions to make once you’ve bet. The banker bet has the lowest edge, at about 1.06%, while the tie bet is far worse, at around 14%.

Live casino

Live casino games stream real dealers from a studio to your screen. You place bets through the on-screen controls, and the dealer spins the wheel or deals the cards in real time. Popular games include live roulette, live blackjack, baccarat and game shows such as Crazy Time.

Live games use the same rules and house edges as their digital versions. That said, they play more slowly, and table limits are usually higher. Read more in our live casino guide.

Casino bonuses and wagering requirements

Most casinos offer new customers a welcome deal, such as free spins or a deposit match. Before you claim one, check three things: what you must deposit or wager to qualify, the wagering on any winnings, and how long you have to use the bonus.

Wagering requirements

Wagering is the number of times you must play bonus funds through before you can withdraw. For example, a £10 bonus with 10x wagering means £100 of bets. Since 19 January 2026, wagering at UK-licensed casinos is capped at 10x. Even so, many of the best offers now have no wagering at all, so winnings are paid as cash.

Other terms to watch

• Max win caps limit how much you can win from free spins or a bonus.
• Expiry dates mean unused spins or funds lapse, often within 7 days or less.
• Game restrictions may limit a bonus to certain slots, or count table games at a lower rate.
• Max bet rules cap your stake while you play with bonus funds.

Our guides to free spins and no deposit bonuses go into more detail. Then compare the latest casino offers, where every deal shows its key terms up front.

Payments and withdrawals

UK casinos accept debit cards (Visa and Mastercard), e-wallets such as PayPal, Apple Pay and Google Pay, and bank transfers including Instant Bank Payment. Credit cards can’t be used. Minimum deposits are usually £5 to £10, and some welcome offers only count certain methods.

Withdrawals normally go back to the method you deposited with. E-wallets and instant bank payments are often the fastest, sometimes within hours, while card withdrawals can take one to three working days. In addition, your first withdrawal may take longer while the casino completes its checks.

See our guides to casino payment methods and withdrawals and ID checks for the details.

Safer gambling tools

Gambling should be fun, so set a budget before you play and only stake money you can afford to lose. Every UK-licensed casino must give you tools to stay in control:

• Deposit limits cap what you can add each day, week or month.
• Reality checks remind you how long you’ve been playing.
• Time-outs pause your account for up to six weeks.
• Self-exclusion blocks your account for six months or more. In addition, GAMSTOP blocks you from every UK-licensed site at once.

If gambling stops being fun, free and confidential help is available from GambleAware and the National Gambling Helpline on 0808 8020 133. Read more in our safer gambling guide.

Online casino glossary

These are the casino terms you’ll see most often. For more than 80 betting and casino terms, see our full glossary of betting and gambling terms.

• RTP: the share of stakes a game pays back over time.
• House edge: the casino’s built-in advantage, equal to 100% minus RTP.
• Volatility: how much a slot’s results swing between small, frequent wins and big, rare ones.
• Wagering: how many times you must play bonus funds through before withdrawing.
• No wagering: winnings are paid as cash you can withdraw straight away.
• Max win cap: the most you can win from a bonus or free spins.
• RNG: the random number generator that decides every result.