Probabilities basics

A probability function scores evidence on a 0 to 1 scale of an event H on a given experiment. P(H) is the probability that H has occurred, and P(¬H) is that it didn’t happen, and 1 − P(H) = P(¬H).

Both of those are unconditional probabilities, if we want to compute the probability of something given some other condition we refer to those as conditional probabilities, in the form of P(H|s), where s corresponds to a given condition.