What is the difference between unconditional and conditional probability?

Unconditional probability is a measure of the liklihood of a particular outcome relating to a series of independent events, where the outcome of one does not effect the outcome of another. For example, consider a bag of 20 marbles: 10 red & 10 blue. The probability of picking a red or blue marble is 1/2. If, on the 1st turn a red marble is picked and replaced, then the probability of picking a red or blue marble on the 2nd turn is also 1/2. In this example, the probability of picking a red or blue marble is unconditional since it is not impacted by the outcome of the previous pick.Conditional probability is similar, but concerns dependent events, where the outcome of one event does effect the outcome of another. Consider the above example: lets assume that on turn 1 a red marble is picked but not replaced. Therefore, for turn 2 there are a total of 19 marbles to choose from, 9 of which are red and 10 of which are blue. Now, the probability of picking a red marble is 9/19 and of picking a blue is 10/19. It is clear that this time the probability does not remain fixed. This is because the events are dependent, meaning that the outcomes are conditional. Resultantly, the probabilities associated with the outcomes of turn 2 are directly impacted by the outcome of turn 1.