Delve into the foundations of modern cosmology with this lecture on Cosmological Perturbation Theory and Cosmic Microwave Background (CMB). Explore key concepts in the Lambda Cold Dark Matter (LCDM) paradigm, including dark matter, dark energy, and the evolution of large-scale structures in the universe. Gain insights into the latest observational techniques and theoretical frameworks used to study cosmic phenomena, from CMB anisotropies to gravitational lensing. Learn about the challenges and opportunities in contemporary cosmological research, including the search for dark matter particles and the implications of gravitational wave detections. Prepare for an in-depth exploration of cutting-edge topics in cosmology, setting the stage for understanding the next decade of discoveries in this rapidly evolving field.