Probability can broadly be divided into two categories i.e. Unconditional and Conditional Probability.
Unconditional Probability: An unconditional probability is the independent chance that a single outcome results from a sample of possible outcomes. The term refers to the likelihood that an event will take place independent of whether any other events take place or any other conditions are present.
Unconditional Probability = Number of times event occurs / Total number of outcome in sample space
Unconditional probability is also known as marginal probability and measures the chance of an occurrence ignoring any knowledge gained from previous or external events. Since this probability ignores new information, it remains constant.
Conditional Probability: A conditional probability is the one where the occurrence of one event affects the probability of the occurrence of another event. Let us suppose there are two events A and B. If Probability of occurrence of event B is dependent on the occurrence or non-occurrence event A then Probability of B can defined as conditional probability. The conditional probability can be written as P(B|A), notation for the probability of B given A.