Introduction to Online Casinos

In our guide section, we aim to give online casino players and people who are just considering gambling online all the important information they need to make smart gambling decisions.

If you are wondering how to choose the best online casino, how casino bonuses and games work (practically and mathematically), as well as how to gamble safely and avoid the dangers of gambling addiction, we hope that this section will help you find the answers to your questions.

For new players and people considering opening their first online casino account, we have prepared a video describing the basics of how online casinos work, as well as five things you should know before playing. Feel free to watch it or continue reading below the video.

This introduction to online casinos contains information on these topics:

How to choose the best online casino for you

There are literally thousands of online casinos in the world, and our casino review team has reviewed all of them. To add to that, new casino sites are being created each month, so the pool of casinos you can choose from keeps growing.

Not all of these casinos are available in all countries but wherever you live, you will almost certainly have a selection from which to choose when deciding where to play.

Choosing the right casino is a crucial decision that will influence your entire online gambling experience. Casinos vary in terms of features, bonuses, game selection, payment methods, and other factors, but their most important aspect is whether they treat their players fairly.

As we witness when reviewing casinos and helping players with their complaints, many online casinos use predatory practices to trick players, decline withdrawals without legitimate reasons, and unfairly increase their profits at the expense of players.

We hope that our list of best online casinos, together with our honest and thorough review of each casino website, will help you make the right choice.

If you want to go further, we invite you to read our article on how to choose the best casino, in which we describe 11 things to look for when choosing a casino. Additionally, feel free to read an article about our casino review process to learn more about what we do to create reviews that paint an honest picture of each casino on the internet.

Note: For more advanced readers, our fair gambling codex describes problematic areas that cause friction between players and casinos, as well as what we think both parties should do to ensure a smooth gambling experience.

Introduction to online casino bonuses

Bonuses are one of the main ways of attracting new players. They generally seem very tempting. That is their purpose, after all. No deposit bonuses give you a chance to play and possibly even win something that's free, while deposit bonuses give you extra funds to play with alongside your deposit. There are other kinds of casino bonuses, but these two are the most prevalent and popular.

However, bonuses come with strings attached, in the form of terms and conditions, which can be extremely limiting. These define what you can and cannot do when playing with an active bonus, or even how much you can win from it. It is crucial that you know about these rules and follow them, as not doing so will most likely result in your bonus and any potential winnings being taken away from you.

Here are some of the most common bonus rules:

  • Wagering requirements – you can't just take your bonus money and withdraw it. First, you need to play with your bonus funds and wager a certain amount in total, in order to convert your bonus funds into real, withdrawable money.
  • Maximum bet – the maximum bet you can place while playing with bonus funds is often limited.
  • Maximum win – the amount of real money you can win from your bonus is often limited, too. This is most common with no-deposit bonuses, but some deposit bonuses have a maximum-win restriction as well.
  • Restricted countries – bonuses are generally available only to players in selected countries.
  • Restricted games – when playing with bonus funds, your game selection is often limited. Bets placed on restricted games don't count towards wagering requirements. Playing restricted games can even lead to your bonus winnings being canceled altogether.

We go into more detail about casino bonuses and rules associated with bonus play in our casino bonus guide. We advise that you check it out before taking advantage of your first casino bonus.

One important consideration for novice players, which we also mention in the video at the beginning of this article, is that it is often better for them to play without a bonus than with it. All the rules described in the terms and conditions make playing with bonus funds very limiting and much less lucrative than it may seem at first glance.

Introduction to gambling mathematics

All casino games are configured to give the casino an advantage, which is also referred to as 'house edge'. This plays a crucial role in the gambling world, as casinos are businesses that need to be profitable to be able to operate long-term. The house edge embedded into all casino games allows them to do that.

Each casino game offers a specific return to player (RTP), which describes the percentage of wagered money that players can expect to get back from the casino in the form of winnings in the long run. The theoretical RTP is almost always (with very specific exceptions) lower than 100%, with the remainder forming the house edge.


European roulette has an RTP of 97.3% and a house edge of 2.7%. This means that when you wager $100, your statistical expected return is $97.30, and the casino can expect to make $2.70 from your bets in the long run. Of course, your actual winnings for a one-off $100 bet will range from $0 to $3,600, depending on the bet you place and the outcome of the game round.

The RTP is a long-term statistical value. The results of individual game rounds can vary greatly, but the overall results will get closer and closer to the expected RTP with an increasing number of game rounds.

This has two crucial consequences:

  • Players can get lucky and win in the short term, even despite the odds being stacked against them. However, if they keep playing, the statistics will catch up with them and they are bound to get into negative numbers sooner or later.
  • Casinos can rely on statistics to be profitable in the long term. Individual players can get lucky and win, but casinos generally have a large number of players. The larger this sample size, the more certain casinos can be that their overall returns will be close to the theoretical value that is assured by the house edge.

There are other mathematical aspects of casino games, the most important one being volatility (also known as variance), which relates to how big individual wins are and how often they occur. To learn more about all of this, check out our article about the mathematics of casino games.

Guides to individual types of casino games

Online casinos allow players to play many types of casino games, which can be found in a huge variety of configurations. These games vary in their complexity, so not all games are suitable for beginners.

For example, in slots, you generally just press a button and wait for the result of the game round to see whether you won or lost. However, games like blackjack and video poker require you to make decisions. Both of these games generally have a very high theoretical RTP, but you need to make the right decisions to achieve this. If you make bad decisions, the actual RTP of your play can fall to very small numbers.

To help you learn the basics of the most popular types of casino games, as well as more advanced strategies to help you play them optimally, we have prepared a series of articles on these games:

Problem gambling and how to gamble safely

Problem gambling, also known as gambling addiction, is a serious issue that can destroy not only the financial situation of affected players but also other aspects of their lives. It is important that you know this and approach gambling, whether online or in land-based venues, with caution.

First of all, gambling should be considered as a form of entertainment, not a way of making money or solving your financial issues. Trying to make money in casinos has ruined many lives, so try to stay away from this approach. The earlier section about gambling mathematics and house edge demonstrates why making money this way simply does not work.

Our article on how to gamble safely can provide you with more information about this, as well as other principles of safe gambling that you should follow to stay safe.

It is part of our section about responsible gambling and help for problem gamblers, in which you can find information on all aspects of gambling addiction, including:

  • Signs of problem gambling and how to diagnose it
  • What causes gambling addiction
  • How to overcome problem gambling
  • What to do if your friend or family member is affected
  • Where to look for help

The safest approach to gambling is, of course, not to gamble at all. However, if you choose to participate in casino games, it's always better to be informed about the potential dangers and participate carefully. Whatever you do, remember to stay safe and seek help if you feel that things are getting out of hand.

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