Fractional Odds

Bookmakers traditionally use fractional odds to illustrate their opinion of the likeliness of an outcome occurring.

For example, if a bookmaker gives odds of 3/1 on Manchester United to win the Premier League, they are effectively saying that if the Premier League was played under exactly the same conditions, three times, Manchester United would only be likely to be Champions once.

If Manchester United were to win, a bettor would win 3 x their stake (plus that stake back).

The term 'odds on' refers to situations where the outcome is deemed very likely to happen. So if Manchester United were considered a strong favourite, they might be odds on at say, 2/7.