Back Bet - A bet placed on the expectation of a particular result happening. For example, if you place a back bet on Team A to win a rugby match, your bet only wins if Team A wins the match, i.e. if Team B wins or it is a draw you lose the bet.

Betting Exchange - Site where you are able to both back an outcome and lay it, i.e. bet that something will not happen, and so allow you to take the place of a bookmaker. The betting exchange has no liability on bets as bets are matched between those willing to lay and back an event at the same odds. Betting exchanges make their profit by charging a small commission on winning bets.

Bookie - See Bookmaker.

Bookmaker - Site where you place back bets.

Free Bet - Commonly offered by bookmakers as an incentive to opening an account. You will normally be credited with the free bet only after placing one or more qualifying bets.

Lay Bet - A bet placed on the expectation that something will not happen. For example, in a football match, a lay bet on Team A will win if Team A do not win the match, i.e Team B wins or it is a draw. Lay bets are placed at betting exchanges.

Liability - The amount you would pay out if you lose a lay bet.

Market - A specific event, or outcomes within an event, where odds are available. For example, full time score and half time score are commonly offered as two separate markets.

Matched Bet - At a betting exchange a matched bet is one where a back and a lay bet have been placed at the same odds. These bets are then said to be matched or confirmed. Alternatively, matched betting (more properly, matched odds betting) is finding lay odds at a betting exchange close to the back odds at a bookmaker, and so taking advantage of free bets.

Odds - The probability of a certain outcome, expressed as a decimal or fraction. At betting exchanges the odds are set entirely by those laying and backing in a market; at bookmakers the odds are set by the bookie themselves.

Qualifying Bet - A bet placed at a bookmaker in order to receive a free bet. Qualifying bets are matched at a betting exchange to ensure minimal losses. A qualifying bet uses your own money, and so should be treated as stake returned when calculating the lay stake.

Stake Returned (SR) - A bet where, if it wins, the original stake is also returned, e.g. a bet of £5 at odds of 5.0 will return £25 - the £20 win plus the £5 stake.

Stake Not Returned (SNR) - A bet where, if it wins, the original stake is not returned, e.g. a get of £5 at odds of 5.0 will return only £20. A SNR free bet will mean you end of with less of the free bet as profit.