Probability is the numeric description of how likely an event is to occur and how likely it is that the proposition is true. It occurs between zero and one, where zero shows impossibility and one indicates certainty. Practically, there are two categories of probability interpretation. These are objectivists and subjectivists. Objectivists allocate numbers to define some physical or objective state of affairs whereas subjectivists allocate number per subjective probability. The field finds its applications in other areas such as computer science, philosophy, mathematics, artificial intelligence/machine learning, finance, statistics and game theory. It is also used in risk assessment and modelling, biology, ecology and financial management. The topics included in this book on probability are of utmost significance and bound to provide incredible insights to readers. It is compiled in such a manner, that it will provide an in-depth knowledge about the theory and practice of this discipline. In this book, constant effort has been made to make the understanding of the difficult concepts of this field as easy and informative as possible, for the readers.