Joint probability refers to the likelihood of two or more events occurring simultaneously. It is expressed mathematically as P(A and B), where A and B are the events in question. For example, if you want to find the probability of rolling a 3 on a die and flipping a heads on a coin, you would calculate the joint probability of these two independent events. To compute joint probability, you can multiply the probabilities of each individual event if they are independent. For instance, if the probability of rolling a 3 is 1/6 and the probability of flipping a heads is 1/2, the joint probability would be P(A and B) = (1/6) * (1/2) = 1/12.