This lecture covers the basics of laser operation, including light-atom interaction, dispersion theory, absorption, gain, line broadening, resonator types, laser systems, noise characteristics, optical fibers, ultrafast lasers, nonlinear frequency conversion, and laboratory visits. It also delves into the electron oscillator model, absorption coefficient, refractive index, absorption, and the Bohr model of the atom. The discussion extends to causality, the Kramers-Kronig relation, damping in single and multiple atom models, quantum vs classical views of the atom, spontaneous emission correction factor, and the Lorentz model's stimulated emission. The lecture concludes with insights into absorption cross-sections, Doppler broadening, and its derivation.