This lecture covers the fundamental concepts of laser operation, including dispersion theory, gain and resonators, different types of laser systems such as gas lasers and solid-state lasers, noise characteristics like linewidth and coherence, optical fibers, ultrafast lasers, nonlinear frequency conversion, and optical detection. The instructor also reviews topics like gain saturation, population and photon rate equations, and relaxation oscillations. Laboratory visits for laser demonstrations are included throughout the course.