Explore a comprehensive lecture on Markov Chains, part of the 2023 Summer School at the Instituto de Matemática Pura e Aplicada. Delve into advanced probability concepts, including convergent sequences, finite unions, arbitrary unions, and image intersections. Learn about elastic equilibrium theorem, probability theory, and measurable functions. Gain insights into recent research applications of Markov Chains. Prerequisite knowledge of elementary probability concepts and basic linear algebra is recommended. The lecture is based on the book "Markov Chains and Mixing Times" by Levin, Peres, and Wilmer, covering selected topics and introducing fundamental Markov Chain concepts.