In probability theory and statistics the odds in favour of an event or a proposition are the quantity p / (1 − p) , where p is the probability of the event or proposition. In other words, an event with m to n odds would have probability m/(m + n). For example, if you chose a random day of the week, then the odds that you would choose a Sunday would be 1/6, not 1/7. The logarithm of the odds is the logit of the probability.
Odds have long been the standard way of representing probability used by bookmakers, though the method of presenting odds varies by location.