Comprehensive and class-tested, this book is designed for a course in Basic Probability to be taken by mathematics, physics, engineering, statistics, actuarial science, operations research, and computer science majors. It assumes a second course in calculus. The aim of the book is to present probability in the most natural way: through a great number of attractive and instructive examples and exercises that motivate the definitions, theorems, and methodology of the theory. Examples and exercises have been very carefully designed to arouse students' curiosity, motivating them to delve into the theory with enthusiasm. Unique discussions of probability problems published in recent journals are featured to stimulate classroom discussion or individual investigation.