This concise textbook covers the full scope of an introductory course in modern probability theory, from elementary combinatorial methods to the central limit theorem, while maintaining mathematical rigor. It includes key topics like the measure extension and the Radon-Nikodym theorems. Designed for a one-semester course, it is well-suited for theoretical mathematics, financial mathematics, insurance, or stochastic modeling students. With 375 exercises, it offers ample opportunities for study and review.