The first half of the course will cover the interaction of quantized atoms with electromagnetic fields, introducing a number of basic concepts such as coherent Rabi transitions vs. rate-equation dynamics, stimulated & spontaneous transitions, and energy & phase relaxations. These will be then used to study a range of applications of atom-field interactions, such as nuclear magnetic resonance, molecular beam and paramagnetic masers, passive and active atomic clocks, dynamic nuclear polarization, pulse sequence techniques to coherently manipulate atomic quantum states, and laser oscillators with applications. We will also touch upon the interaction of quantized atoms with quantized fields, discussing the atom + photon (Jaynes-Cummings) Hamiltonian, dressed states, and cavity quantum electrodynamics. The second half will cover the classical interaction of electromagnetic fields with matter, with special attentions to collective electrodynamics in particular, magnetohydrodynamics and plasma physics with applications in astrophysics, space physics, and Bloch electrons in crystalline solids.