How online casinos work
One bet through the stack: account, wallet, game client, RNG or live stream, settlement. Mechanics from regulator rulebooks — no sites, no rankings, no sign-up steps.
Answer first
90s| Layer | What it does | What the rulebook checks |
|---|---|---|
| Client | Screen on your device: buttons and animation | Secured link to the system |
| Account & wallet | Verified identity, one balance, set limits | Identity and age before play |
| Game client | Shows rules, takes the bet, shows the result | Rules and charges readable |
| RNG or live table | Software draws the outcome, or a dealer deals | Tested RNG, verified dealer result |
| Settlement | Stake leaves the balance, win goes back in | Last game and balance viewable |
| Records | Every session can be rebuilt from logs | NJ: kept 10 years minimum |
Progress
How online casino games work: one bet, five hops
- 1
Client
You tap Bet — the device sends a request, not a result
- 2
Account & wallet
System checks the session and balance, then takes the stake
- 3
Game client
Game software holds the rules, paytable, and screen
- 4
RNG or live table
Server draws the outcome, or the dealer’s result is verified
- 5
Settlement
Stake settled against the result; balance and history update
The screen is the last hop, not the first. By the time reels spin or a card flips on your device, the outcome is already fixed on the system side.
On the machine
How online casino slots work: drawn first, shown second
Drawn: a line wins
The display must match the RNG draw — it cannot add or remove a win
Drawn: no line
No secondary pick to stage a near miss (GLI-19 §4.5.2)
Next round
Independent of the last one — no hot or cold game
Same idea as a machine on a casino floor. Credits, paylines, and denominations are covered in How slots work.
On the felt
Cards: software shuffle vs live camera
RNG table
The shuffle comes from the RNG; the hidden card is unreadable by anyone
Live studio table
Real cards on camera; the dealer-verified result is what posts
Before wagers lock
The outcome must stay inaccessible until the wager is final
Row three is the rule behind the other two: nobody should be able to read a result before the bet is locked in.
Software (RNG) game vs live-dealer table
| Question | Software (RNG) game | Live-dealer table |
|---|---|---|
| What decides the result | An RNG draw on the system | Physical cards, wheel, or dice on camera |
| Who runs the round | Game software | A dealer in an operator-controlled studio |
| What you watch | An animation of the draw | Real-time video of the table |
| What posts to your balance | The RNG outcome | The dealer-verified result |
| What the rulebook stresses | RNG strength and independence | Result verification, and a way to void |
Rows are generic. Details differ by state and game — read the rules screen of the game you open.
Sequence
One round, step by step
Step 01
Log in to your own account
Access is limited to the account holder: username, password, an optional stronger login, and a notice each time the account is accessed unless you opt out (NJ 13:69O-1.4).
Step 02
Open a game and read its rules
Rules, payouts, and any charges such as rake must be readable before and during play (NJ 13:69O-1.5).
Step 03
Place the bet
Play starts only after you place a wager and activate it. The stake leaves your balance, and a bet that would push it below zero is refused.
Step 04
The system draws the result
An RNG picks the outcome on the system side. At a live table the dealer deals and the result is verified. The screen shows only what was determined.
Step 05
Settle and update the balance
A win is credited; a loss stays spent. If you disconnect mid-game, the operator’s approved rules decide how the round finishes.
Step 06
Review the trail
You can view the last game outcome and balance change, even after an outage. The operator keeps data to recreate the session.
Your turn
Who does what in the stack
Operator
The licensed company that holds the permit, runs the account system, and answers to the regulator for every round.
Game supplier
Builds game software and RNG code, then submits it for approval before it can be offered. This page names the role, not companies.
Independent test lab
Reviews RNG source code and checks outputs with statistical tests before approval. GLI-19 names chi-square, runs, and serial-correlation tests.
Regulator
Writes the rules, approves software, can query system data, and can order gaming stopped. New Jersey’s DGE and Nevada’s NGCB are the two quoted here.
Catalog fields
RNG meaning and other words in the rulebook
RNG
Outcome source
Random number generator: a physical device or math algorithm whose outcomes cannot be predicted (NJ definition). Games draw from it each round.
Tip: Past rounds do not help you read the next one.
seed
Starting value
A software RNG needs a start point. NJ requires a seed set by an uncontrolled event, so the RNG never begins from the same value every time.
Tip: A restart does not replay old results.
rescale
Big number, small range
Mapping a huge random number onto 52 cards or 37 pockets without favoring any of them. NJ: shorter ranges must stay equally probable.
Tip: Labs read this code for bias.
session ID
One login, one trail
NJ gives each patron session a unique identifier. Nevada’s standard logs player and game session IDs, plus balances at session start and end.
Tip: Disputes are settled from this trail.
GAT
Software fingerprint
Gaming Authentication Tool: a check that live software matches the approved copy. NJ systems authenticate control programs at least every 24 hours.
Tip: A failed check means stop and tell the regulator.
RTP
Long-run return
Theoretical share of wagers a game returns over a very large number of rounds, kept on a par sheet. It says nothing about one session.
Tip: Operators audit theory against actual results.
Terms come from NJ rules, Nevada technical standards, and GLI-19. Wording varies by jurisdiction; the ideas repeat.
Watch outs
Myths about online casino software
01The animation decides the result
Reels and cards are display. The outcome is drawn first, and the screen may only show what the RNG or the verified dealer result determined.
02A game is “due” or “hot”
RNG draws must be statistically independent. Earlier results do not change the next round (NJ 13:69E-1.28G; GLI-19 §4.5.2).
03A slow connection changes the odds
GLI-19 says bandwidth and link quality must not affect events of chance. A dropped link triggers disconnect rules; it does not reroll the draw.
04Software quietly adapts to you
GLI-19 bars games from changing bonus likelihood or return based on past payouts. Labs review source code for hidden switches.
05Looks professional, so it is licensed
A polished app proves nothing. A regulated stack has a named permit, approved software, and published rules. Look for the regulator, not the logo.
At the door
Six things a regulated stack lets you check
Gate pass
21+
Account tied to you
A single account per person at each operator, identity and age verified before play. Funds cannot be moved to another player (NJ).
Last game on screen
You can look back at the previous outcome and balance change, even after a dropped connection.
Limits you can set
NJ systems must offer deposit and spend limits (daily, weekly, monthly) plus a daily time limit. Lowering a limit applies by your next login.
Rules and fees up front
Payout rules and charges such as rake must be readable before and during play.
Funds held apart
NJ requires a separate bank account that covers every player balance, funds on game, and pending withdrawals.
Help line on screen
NJ requires the 1-800-GAMBLER message on the log-in screen. Other states set their own wording.
Rulebook features, not endorsements of any site. New Jersey is quoted because its text is public and specific; other states differ.
Go play
Where to play in Las Vegas
Tap a resort — each row opens that casino’s CasinoList page (hours, parking, loyalty, floor facts). Sorted by published table units when we have them — confirm on property.
Open a casino page
Real listings · not adsRanked lists
Open a shortlist that matches this guide
Same intent, inventory first — tap through for the places we already publish for Las Vegas.
Online catalogue
Licensed online casino states
Where commercial iGaming is live on our matrix — operator names stay on licence cards inside /en/online/.
Open online pageAfter the 90 seconds
Questions before and after you play
A 90-second guide cannot cover every table moment. Tap a group, then a question — answers are short paragraphs, not one-liners.
01The basics
How do online casinos work?
An online casino is a stack of systems, not one website. You log in to a verified account, the system checks your balance and takes your stake, game software shows the rules, an RNG (or a live dealer feed) produces the result, and settlement updates your balance and history. Regulators write rules for each layer: identity checks, secured communications, tested RNGs, and records the operator must keep.
How does online casino software work?
Game software is a client that talks to a server. The client shows rules, buttons, and animation; the server holds your account state and draws the outcome. In regulated systems, the software must be approved before it is offered, and the system must be able to check that live code matches the approved copy. New Jersey requires that authentication at least every 24 hours and on demand.
What does RNG mean in a casino?
RNG means random number generator: a physical device or math algorithm that generates outcomes that cannot be predicted, in New Jersey’s wording. A game asks it for a number each round, then maps that number to reels, cards, or pockets. Rules require the draws to be statistically independent, which is why a past run tells you nothing about the next round.
How do online casino games work from bet to payout?
You place a wager and activate play, the stake comes out of your balance, the system draws the outcome, and the screen shows what was drawn. A win is credited to the balance; a loss stays spent. The game rules, payouts, and any charges must be readable before and during play, and you can view the previous game and balance change afterward.
How do online casino slots work?
A software slot draws its result from an RNG when you press Spin; the spinning reels are display. The paytable then scores the drawn symbols against active lines or ways. Rules say the screen may only show what was drawn, with no secondary pick to stage a near miss, and each spin is independent. For credits and paylines, see How slots work.
02Fairness and testing
Who tests the random number generator?
Independent test laboratories review it before approval, and regulators publish the standards. GLI-19, which GLI distributes free, has the lab review RNG source code for bias and hidden switches, then run statistical tests on the final outcomes at a 99% confidence level. Nevada’s Technical Standard 1 sets its own RNG tests, and New Jersey’s rule names chi-square, mono-bit, and runs tests.
Can a game change the odds based on how I play?
Not in a regulated game. GLI-19 says a game must not adjust the likelihood of a bonus based on earlier awards, and must not adapt its theoretical return to past payouts. Independence is the point of an RNG. Labs review code for hidden switches, and operators compare theoretical return with actual results to catch drift.
What happens if my connection drops mid-round?
The operator’s approved rules decide. In New Jersey, if no input is needed the game completes with the RNG result and updates your account. If input is needed, the game can return you to the same state, cancel within six months with a wager return or forfeit, or choose for you. You can view the outcome afterward.
03Money, records, and live tables
Where does my balance live?
It lives in the operator’s account system, tied to one verified account, not in the game client on your device. Regulators require the system to block bets above your balance and to log changes. New Jersey also requires a separate bank account covering all player balances, funds on game, and pending withdrawals, and bars transfers between players.
How is a live-dealer game different from an RNG game?
At a live table the result comes from physical cards, a wheel, or dice handled by a dealer on camera, and what posts to your balance is the dealer-verified result. New Jersey’s simulcast rule requires real-time video, a control server that records verified results before posting, and a way to void a result. An RNG game draws on the system side instead.
04Land floors and scope
How is this different from a casino floor?
On a floor, the slot or table sits in front of you in a licensed building, and a cage hands you cash. In the remote stack, your device is only a client; the draw, the balance, and the records sit on the operator’s systems. The RNG idea and independence rules are shared. For the floor version, see What are land-based casinos?
Does CasinoList list or rank online casinos?
No. This page explains mechanics from regulator and test-lab documents. It does not name operators or suppliers, rank them, or link to them, and it is not a how-to for opening an account. The venue cards on this site are licensed land floors with official sources.
Is online casino gaming legal where I live?
It depends on your state, and permission is a separate decision from land casino licensing. This page covers mechanics, not legality. For how US states license gaming at all, read Is casino gambling legal in the US? and check your state regulator’s own pages. Adults only: 21+ is the usual line for casino gaming.
Sources
- NJ Division of Gaming Enforcement — N.J.A.C. 13:69O Internet and mobile gaming · accessed Oct 12, 2026Accounts, sessions, server-based games, table game simulcasting, logging (13:69O-1.2 to 1.8).
- NJ Division of Gaming Enforcement — N.J.A.C. 13:69E (§1.28G RNG standards) · accessed Oct 12, 2026RNG definition, seeding, statistical tests, rescaling, outcome display (13:69E-1.28G).
- Nevada Gaming Control Board — Technical Standard 1 (§1.400 RNG) · accessed Oct 12, 2026Chi-squared limits, seeding, hidden outcome sets; CSPRNG for devices approved from January 1, 2027.
- Nevada Gaming Control Board — Technical Standard 6, interactive gaming systems · accessed Oct 12, 2026Player and game sessions (§6.120). Revision on the Board site dated 1/27/2012; Notice 2026-52 proposes updates.
- GLI-19 Standards for Interactive Gaming Systems v3.0 · accessed Oct 12, 2026Test-lab standard published free; RNG review (ch. 3), game outcome and fairness rules (§4.5–4.6). A v4.0 draft is open for comment.