Gambling has had many different meanings depending on the cultural and historical context in which it is used. Currently, in western society, it has an economic definition, referring to "wagering money or something of material value on an event with an uncertain outcome with the primary intent of winning additional money or material goods". Typically the outcome of the wager is evident within a short period of time. Legal aspects Because religious authorities generally disapprove of gambling to some extent, and because gambling can have adverse social consequences, most legal jurisdictions limit gambling to some extent. Some Islamic nations prohibit gambling; most other countries regulate it. Most countries' laws do not recognise wagers as contracts, and views any consequent losses as debts of honour, unenforceable by legal process. Thus organized crime often takes over the enforcement of large gambling debts, sometimes using violent methods. Because contracts of insurance have many features in common with wagers, legislation generally makes a distinction, typically defining any agreement in which either one of the parties has an interest in the outcome bet upon, beyond the specific financial terms, as a contract of insurance. Thus a bet on whether one's house will burn down becomes a contract of insurance, as one has an independent interest in the security of one's home. Furthermore, many jurisdictions, local as well as national, either ban or heavily control (by licensing) gambling. Such regulation generally leads to gambling tourism and illegal gambling, the latter often under the auspices of organized crime. Such involvement frequently brings the activity under even more severe moral censure and leads to calls for greater regulation. Conversely, the close involvement of governments (through regulation and gambling taxation) has led to a close connection between many governments and gambling organisations, where legal gambling provides much government revenue, such as in Monaco. There is general legislation requiring that the odds in gambling machines are fair (i.e. statistically random), to prevent manufacturers from making some high-payoff results impossible (since these have very low probability, this can quite easily pass unnoticed). Actions typically not regarded as gambling Emotional or physical risk-taking where what is being risked is not money or material goods (e.g., skydiving, running for office, asking someone for a date, etc.) Buying insurance, as the primary intent of the purchase is to protect against loss, rather than to collect All forms of 'investment' (stock market, real estate) with positive expected returns, economic utility, and some underlying value independent of the risk being undertaken Starting a new business, as time and effort are also being wagered and the outcome is not determined in a short period of time Situations where the possibility of winning additional money or material goods is a secondary or incidental reason for the wager/purchase (e.g., buying a raffle ticket to support a worthy cause) Prediction markets or knowledge exchanges where the outcome is to encourage the development of market-based mechanisms for resolving questions of science, technology, management, strategy, planning, policy, etc. Gambling variables There are three variables common to all forms of gambling: How much is being wagered, the initial stake (in money or material goods). The predictability of the event. In mechanical or electronic gambling such as lotteries, slot machines and bingo, the results are random and unpredictable; no amount of skill or knowledge (assuming machinery is functioning as intended) can give an advantage in predicatability to anyone. However, for sports events such as horse racing and soccer matches there is some predictability to the outcome; thus a person with greater knowledge and/or skill will have an advantage over others. The odds agreed between the two (or more) parties to the wager; where there is a house or a bookmaker, the odds are (quite legally) arranged in favour of the house. The expected value, positive or negative, is a mathematical calculation using these three variables. The amount wagered determines the scale of an individual wager (bet); the odds and the amount wagered determine the payout if successful; the predicability determines the frequency of success. Finally the frequency of success times the payout minus the amount wagered equals the "expected value" The skill of a gambler lies in understanding and manoeuvring the three variables so that the "actual value" is positive over a series of wagers. Psychological aspects Though many participate in gambling as a form of recreation or even as a means to gain an income, gambling, like any behavior which involves variation in brain chemistry, can become a psychologically addictive and harmful behavior in some people. Reinforcement phenomena may also make gamblers persist in gambling even after repeated losses. Because of the negative connotations of the word "gambling", casinos and race tracks often use the euphemism "gaming" to describe the recreational gambling activities they offer. The Russian writer Dostoevsky portrays in his novella The Gambler the psychological implications of gambling and how gambling can affect gamblers. He also associates gambling and the idea of "getting rich quick", suggesting that Russians may have a particular affinity for gambling. Dostoevsky shows the effect of betting money for the chance of gaining more in 19th-century Europe. The association between Russians and gambling has fed legends of the origins of Russian roulette.