Luck or fortuity is good or bad fortune in life caused by accident or chance, and attributed by some to reasons of faith or superstition, which happens beyond a person's control. The term luck is pervasive in common speech. There are at least two senses people usually mean when they use the term, the proscriptive sense and the descriptive sense. In the proscriptive sense, luck is the supernatural and deterministic concept that there is a force. This Force proscribes that certain events occur very much the way the laws of physics will proscribe that certain events occur. It is the proscriptive sense that people mean when they state that they do not believe in luck. In the descriptive sense, luck is merely a descriptive name we give to events after they occur which we find to be fortuitous. Cultural views of luck vary from perceiving luck as a matter of random chance to attributing to luck explanations of faith or superstition. For example, the Romans believed in the embodiment of luck as the goddess Fortuna, while the atheist and philosopher Daniel Dennett believes that luck is mere luck rather than a property of a person or thing. Lucky symbols have widespread global appeal. They are always meaning a form of superstition. There is also a series of spiritual or supernatural beliefs regarding fortune. These beliefs vary widely from one to another, but most agree that luck can be through spiritual means by performing certain rituals or by avoiding certain circumstances. One such activity is prayer, a religious practice in which this belief is particularly strong. Many cultures and religions worldwide place a strong emphasis on a person's ability to influence their fortune by ritualistic means, sometimes involving sacrifice, omens or spells. Others associate luck with a strong sense of superstition, that is, a belief that certain taboo or blessed actions will influence how fortune favors them for the future. Luck can also be a belief in an organization of fortunate and unfortunate events. Luck is a form of superstition, which is differently by different individuals. Famous Swiss psychiatrist, Carl Jung, who founded analytical psychology, coined the term synchronicity, which he described as a meaningful coincidence. Christianity and Islam believe in the will of a supreme being rather than luck as the primary influence in future events. The degrees of this Divine Providence vary greatly from one person to another; however, most acknowledge providence as at least a partial, if not complete influence on luck. Christianity, in its early development, accommodated many traditional practices which at different times, accepted omens and practiced forms of ritual sacrifice in order to divine the will of their supreme being or to influence divine favoritism. The concept of Divine Grace as believers describe it closely resembles what others refer to as luck. Mesoamerican religions, such as the Aztecs, Mayans and Incas, had particularly strong beliefs regarding the relationship between rituals and luck. The Mayans also believed in blood offerings, where men or women wanting to earn favor with the gods, to bring about good luck, would cut themselves and bleed on the gods' altar. Many traditional African practices, such as voodoo and hoodoo, have a strong belief in superstition. Some of these religions include a belief that third parties can influence an individual's luck. Shamans and witches are both respected and feared, based on their ability to cause good or bad fortune for those in villages near them.

Online casinos, also known as virtual casinos or Internet casinos are online versions of traditional brick and mortar casinos. Online casinos enable gamblers to play and wager on casino games through the Internet.

Online casinos generally offer odds and payback percentages that are comparable to land-based casinos. Some online casinos claim higher payback percentages for slot machine games, and some publish payout percentage audits on their websites. Assuming that the online casino is using an appropriately programmed random number generator, table games like blackjack have an established house edge. The payout percentage for these games is established by the rules of the game.

Online casinos can be divided into two groups based on their interface: web-based and download-only casinos. Some casinos offer both interfaces.

Some casinos offer 'Live gaming', either exclusively, or as part of a wider online casino offering. In live online casinos, popular casino games such as roulette and blackjack are dealt by real dealers in casino studios, in an attempt to convey more of the atmosphere of a physical casino. Player actions including chat such as 'hit' in the game of blackjack may be transmitted to the dealer; in some online casinos more than one player may 'sit' at a particular 'seat' on the table, and in this case there is no interactivity between player and dealer. The question of which player s requested the extra card that the dealer dealt and which chose to 'stand' will be handled by the software. It is usual for players to be able to observe a video feed of the action, and equally common for players to opt to turn it off, if they lack the bandwidth - as the cards are read by OCR and other technology, the video feed is only ever a visual cue.

Web-based online casinos

Web-based online casinos are websites where users may play casino games without downloading software to the local computer. Games are mainly represented in the browser plug-ins Macromedia Flash, Macromedia Shockwave, or Java and require browser support for these plug-in. In addition, bandwidth is needed since all graphics, sounds and animations are loaded through the web via the plug-in. Some online casinos also allow game play through a plain HTML interface. Apple devices such as IPod, IPad and IPhone cannot play Flash games as the technology is not supported.

Download-based online casinos

Download-based online casinos require the download of the software client in order to play and wager on the casino games offered. The online casino software connects to the casino service provider and handles contact without browser support. Download-based online casinos generally run faster than web-based online casinos since the graphics and sound programs are located within the software client, rather than having to be loaded from the Internet. On the other hand, the initial download and installation of a download-based online casino client does take time. As with any download from the Internet, the risk of the program containing malware does exist. Still the graphics and sounds at download-based online casinos are most of the time much better than those at web-based online casinos.