Upon successful completion of this course the students will be able to demonstrate proficiency in basic principles of interaction of light and matter and their application to the spectroscopy of atoms and molecules. The lecture topics will include the theory of one, two and many-electron atoms, their spectra and the effects of external electric and magnetic fields. We will consider rotational, vibrational and electronic spectra of diatomic molecules, including microwave, infrared, Raman and visible/ultraviolet spectroscopic techniques, study the fundamentals of polyatomic molecular spectroscopy, and will explore the mechanisms defining the width and shape of spectral lines.