Discrete Spaces of Elementary Events.- An Arbitrary Space of Elementary Events.- Random Variables and Distribution Functions.- Numerical Characteristics of Random Variables.- Sequences of Independent Trials with Two Outcomes.- On Convergence of Random Variables and Distributions.- Characteristic Functions.- Sequences of Independent Random Variables. Limit Theorems.- Large Deviation Probabilities for Sums of Independent Random Variables.- Renewal Processes.- Properties of the Trajectories of Random Walks. Zero-One Laws.- Random Walks and Factorisation Identities.- Sequences of Dependent Trials. Markov Chains.- Information and Entropy.- Martingales.- Stationary Sequences.- Stochastic Recursive Sequences.- Continuous Time Random Processes.- Processes with Independent Increments.- Functional Limit Theorems.- Markov Processes.- Processes with Finite Second Moments. Gaussian Processes.- Appendices.