Bayesian probability is a reasonable expectation representing a state of knowledge or as quantification of a personal belief regarding some outcome. Bayesian probability contrasts to the commonly used frequentist interpretation of probability which is based on the frequency or propensity of some outcome. Bayesian probability represents a level of certainty relating to a potential result. This is in comparison to a frequentist probability that shows the frequency with which a certain result will occur over any amount of trials.