This lecture introduces the basic concepts of probability, starting with the definition of sample space and events. The instructor explains the fundamental actions that define probability, such as the sample space, events, and intersections. The lecture covers the concept of probability as a measure of uncertainty, illustrating how to calculate probabilities for different scenarios. It also delves into the principles of disjoint events, complements, and the union of events. The lecture concludes with a discussion on the importance of independence between events and the application of Bayes' rule in probability calculations.