Probability can be generally defined as a measure of how likely some event will occur. The event could be an explosion, a lottery win or perhaps cancer induction. Mathematically speaking, the value of probability varies between 0 and 1 where 0 means an event will never occur whilst 1 means the event will definitely occur. The probability of a hazard such as cancer can be multiplied by the severity of that hazard (e.g. in terms of years of life lost, quality of life lost, effect on society) to give the Risk. In Radiation Protection, that risk can be expressed in terms of radiation Dose (by considering the overall Radiation Detriment).