Gambling (or betting) is any behavior involving risking money or property (making a wager or placing a stake) on the outcome of a game, contest, or other event in which the outcome of that activity depends partially or totally upon chance or upon one's ability to do something.

In extended usage, gambling may also refer to engaging in any high-risk behavior in which decisions occur based upon incomplete knowledge - for example, high-risk stock investments (see speculation), difficult and potentially costly business or non-business ventures, or even personal relationships.

Gambling games may predate recorded history, with examples recorded in virtually all of the ancient civilizations.

Legal aspects

Because religious authorities generally frown on gambling to some extent, and because of various perceived social costs, most legal jurisdictions censure gambling to some extent. Islamic nations officially prohibit gambling; most other countries regulate it. In particular, in the majority of circumstances - and perhaps all cases - the law does 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 (license) 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. Note Monaco.

There is generally legislation requesting 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).
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 short story 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.
Help for addictive gamblers

Many organizations exist to help individuals with a gambling addiction. They include Gamblers Anonymous and Gambler's Help(Australia).

Types of gambling

Casino games

"Beatable" casino games

With proper strategy, a smart player can create a positive mathematical expectation.

• Poker (Also recognised as a game of skill)
• Blackjack -- with card counting
• Video poker -- with proper pay table or progressive jackpot
• Pai Gow Poker and Tiles -- player-dealt
• Sports betting
• Horse racing (parimutuel)
• Slot machines -- only linked, multi-player jackpots whose prizes have reached a certain point

"Unbeatable" casino games

All players must lose in the long run, no matter what strategy they choose.

• Baccarat
• Craps
• Roulette
• Keno
• Casino war
• Faro (All but extinct in recent times)
• Pachinko
• Sic Bo
• Let It Ride
• 3-card Poker
• 4-card poker
• Red Dog
• Pyramid Poker
• Caribbean Stud Poker
• Spanish 21 -- without counting

Non-casino gambling games

• Lottery
• Mahjong
• Fan-Tan
• Dice-based
  o Backgammon
  o Liar's dice
  o Passe-dix
  o Hazard
• Card games
  o Liar's poker
  o Bridge
  o Basset
  o Lansquenet
  o Piquet
  o Put
• Coin-tossing
  o Head and Tail
  o Two-up (Australian casinos offer versions of two-up)
• Confidence tricks
  o Three card monte
  o The shell game
• Carnival Games
  o The Razzle
  o Hanky Pank
  o Penny Falls
  o Six-Cat
  o The Swinger
  o The Push-up Bottle
  o The Nail Joint
• Con Games (in bars)
  o Put and Take
  o The Smack
  o The Drunken Mitt

Fixed-odds gambling

Fixed-odds gambling and Parimutuel betting frequently occur at or on the following kinds of events:

• Horse racing (see below)
• Greyhound racing
• Jai alai
• Football matches (particularly on Association and American football)
• Golf
• Tennis
• Cricket
• Baseball
• Basketball
• Ice hockey
• Rugby (League and Union)
• Snooker
• Motor Racing
• Boxing
• Darts

In addition many bookmakers offer fixed odds on a number of non-sports related outcomes, for example the direction and extent of movement of various financial indices, whether snow will fall on Christmas Day in a given area, the winner of television competitions such as Big Brother, and so forth. Interactive prediction markets also offer trading on these outcomes, with "shares" of results trading on an open market.

Gambling on horse races

One of the most widespread forms of gambling involves betting on horse races, most commonly on races between thoroughbreds or between standard breds.

Wagering may take place through parimutuel pools; or bookmakers may take bets personally. Parimutuel wagers pay off at prices determined by support in the wagering pools, while bookmakers pay off either at the odds offered at the time of accepting the bet; or at the median odds offered by track bookmakers at the time the race started.

In Canada and the United States, the most common types of bet on horse races include:

• win – to succeed the bettor must pick the horse which wins the race.
  place – the bettor must pick a horse which finishes either first or second.
• show – the bettor must pick a horse which finishes first, second, or third.
• exacta, perfecta, or exactor –the bettor must pick the two horses which finish first and second and specify which will finish first
• quinella or quiniela – the bettor must pick the two horses which finish first and second, but need not specify which will finish first.
• trifecta or triactor – the bettor must pick the three horses which finish first, second, and third and specify which will finish first, second and third.
• superfecta – the bettor must pick the four horses which finish first, second, third and fourth, and specify which will finish first, second, third and fourth.
• double – the bettor must pick the winners of two successive races; most race tracks in Canada and the United States take double wagers on the first two races on the program (the daily double) and on the last two (the late double).
• triple – the bettor must pick the winners of three successive races; many tracks offer rolling triples, or triples on any three successive races on the program. Also called pick three.
• sweep – the bettor must pick the winners of four or more successive races. In the US, this is usually called pick four and pick six, with the latter paying out a consolation return to bettors correctly selecting five winners out of six races, and with "rollover" jackpots accumulating each day until one or more bettors correctly picks all six winners.

Win, place and show wagers class as straight bets, and the remaining wagers as exotic bets. Bettors usually make multiple wagers on exotic bets. A box consists of a multiple wager in which punters bet all possible combinations of a group of horses in the same race. A key involves making a multiple wager with a single horse in one race bet in one position with all possible combinations of other selected horses in a single race. A wheel consists of betting all horses in one race of a bet involving two or more races. For example a 1-all daily double wheel bets the 1-horse in the first race with every horse in the second.

People making straight bets commonly employ the strategy of an 'each way' bet. Here the bettor picks a horse and bets it will win, and makes an additional bet that it will show, so that theoretically if the horse runs third it will at least pay back the two bets. The Canadian and American equivalent is the bet across (short for across the board): the bettor bets equal sums on the horse to win, place, and show.

In Canada and the United States punters make exotic wagers on horses running at the same track on the same program. In the United Kingdom bookmakers offer exotic wagers on horses at different tracks. Probably the Yankee occurs most commonly: in this the bettor tries to pick the winner of four races. This bet also includes subsidiary wagers on smaller combinations of the chosen horses; for example, if only two of the four horses win, the bettor still collects for their double. A Trixie requires trying to pick three winners, and a Canadian or Super Yankee trying to pick five; these also include subsidiary bets. The term nap identifies the best bet of the day.

A parlay (US) or accumulator (UK) consists of a series of bets in which bettors stake the winnings from one race on the next in order until either the bettor loses or the series completes successfully.

Sports betting

Betting on team sports has become an important service industry in many countries. For example, millions of Britons play the football pools every week. At sports betting, players may beat the bank.

Most jurisdictions in Canada and the United States regard sports betting as illegal (Nevada offers full sports betting and the Canadian provinces offer Sport Select - government-run sports parlay betting). However, millions engage in sports betting despite its illegality.

In Canada and the United States the most popular sports bets include:

• against the spread - the bettor wagers either that the favoured team will win by a specified number of points or that it will not. Giving the points involves betting the favourite, and taking the points means betting the underdog. See point spread. A team covers the spread if it wins the game with the score modified by the spread. If Dallas and Washington are playing and the spread is (Dallas -7), then Dallas has to win by at least 8 points to cover. Half-point spreads are also possible and the spread may not change.
• against odds - the most popular types of bets against odds comprise simple bets that a team will win and over-under (bets on the total points, runs, or goals scored by both teams). In making an over-under bet, the bettor wagers that the total will exceed or fall short of a total specified by the bookmaker.
• against a combination of odds and spread

In sports betting, a parlay involves a bet that two or more teams will win. In the United States gamblers have made the parlay card one of the most common forms of sports betting: here bettors wager on the outcomes of two or more games. If all their picks win, they collect. Most such betting occurs in workplaces.
Scratchcards

A scratchcard is a small piece of card where an area has been covered by a substance that cannot be seen through, but can be scratched off. Under this area are concealed the items/pictures that must be 'found' in order to win.

The generic scratchcard requires the player to match three of the same prize amounts. If this is accomplished, they win that amount. Other scratchcards involve matching symbols, pictures or words.

Scratchcards are a very popular form of gambling due to their low cost. However, the low cost to buy a scratchcard is offset by the smaller prizes, compared to casino jackpots or lottery wins.


Other types of betting

One can also bet with another person that a statement is true or false, or that a specified event will happen (a "back bet") or will not happen (a "lay bet") within a specified time. This occurs in particular when two people have opposing but strongly-held views on truth or events. Not only do the parties hope to gain from the bet, they place the bet also to demonstrate their certainty about the issue. Some means of determining the issue at stake must exist. Sometimes the amount bet remains nominal, demonstrating the outcome as one of principle rather than of financial importance.
Arbitrage betting

Arbitrage betting, deceptively advertised as no-risk or risk-free betting, is a special case of betting on events offered by betting websites which is not gambling but rather an unusual investment practice.
Staking systems

Many people have formulated staking systems in an attempt to "beat the bookie", but most still accept that no staking system can make an unprofitable system profitable over time. Widely-used systems include:

• Fixed stakes – a traditional system of staking the same amount on each selection. This method suits conservative punters if the stake remains below 5% of the bank.
• Fixed profits – the stakes vary based on the odds to ensure the same profit from each winning selection. This method suits conservative punters well, although if the profitability of one's bets varies independently of the odds the bettor simply reduces his or her cash flow.
• Due-column betting – A variation on fixed profits betting in which the bettor sets a target profit and then calculates a bet size that will make this profit, adding any losses to the target. For example, to make a target of $100 profit a bettor would wager $50 at odds of 2 to 1. If the bet loses, the target becomes $150. If the next bet is also at odds of 2 to 1, the wager therefore becomes $75. This type of wagering can prove ruinous in the long run.
• Kelly (optimal) – the punter needs to estimate fair odds (in the European/decimal format) and then calculate the stake using :

Stake= (Odds/(Fair odds-1))/(Odds-1) Many times used with a divider (most commonly 4 or 8) depending on your bankroll (for betting)

• Martingale – A system based on staking enough each time to recover losses from previous bet(s) until one wins. It is usually applied to even-money bets such as red/black on roulette. The Martingale guarantees failure in the long run - it would only work if the bettor has an unlimited bankroll, the bookmaker has no limit on the size of bets and neither party ever dies. However, it can usually be used to gain a small win in the short run, given a bankroll large enough to survive a streak of five or six losses.

List of notable wagers

• The man who broke the bank at Monte Carlo
• Pascal's wager
• St. Petersburg paradox
• The wager in Around the World in Eighty Days
• Wager between John Pierpoint Morgan and Hugh Cecil Lowther, 5th Earl of Lonsdale on whether a man could walk round the world and remain unidentified
• Wager between Julian Simon and Paul Ehrlich on commodity prices
• The annual Nenana Ice Classic, when the inhabitants of Alaska bet on when the ice will break on the Tanana River.
• Wager on Black hole information paradox: Stephen Hawking and Kip Thorne against John Preskill

Associated word usage

• The English expression "I bet that xxxxx", meaning "I consider it very probable that xxxxx", need not carry any suggestion of the speaker intending to gamble.
• The English word hazard originated as Arabic az-zār or al-zār, which meant a type of dice game. Compare also the English word "dicey" meaning "risky".
• Scientists have dubbed certain random-number-based calculation algorithms the "Monte Carlo method".
• Even money, as a gambling term, describes a wagering proposition with even odds - in other words, if one loses a bet, one stands to lose the same amount of money that the winner of the bet would win (less, of course, the vigorish or "juice"). The term has come to have meaning in the wider English usage beyond actual gambling, however, as a way of describing an event whose occurrence is about as likely to occur as not, as in "It's even money that it will rain today". Compare 50 50.