Probability refers to the likelihood that an event will occur. By analyzing the available data, we can predict the chances of a certain event in terms of a number. We can do simple experiments to become familiar with the different outcomes that are possible, and we can develop and apply some mathematical laws of probability to help us analyze such experiment.

We shall often use experiments like tossing coins, rolling dice, drawing cards from a pack and selecting colored balls from a box, because they are simple to visualize and will give us basic ideas of probability theory.

Probability denotes the possibility of the outcome of any extent to which any event is likely to happen. Probability of an event happening is a ratio of the number of favorable outcomes to the total number of outcomes.

Mathematically, probability of an event happening is a ratio of the number of favorable outcomes to the total number of outcomes. It can be formulated as follows:

Range of probabilities is from 0 to 1, where 0 represents impossible event and 1 represents a probable event.

The outcome (sample point) is the result of an experiment. The outcomes which insure the happening of a particular result are said to be favorable outcomes to that particular result.