Atoms and Their Spectroscopic Properties has been designed as a reference on atomic constants and elementary processes involving atoms. The topics include energy levels, Lamb shifts, electric multipole polarizabilities, oscillator strengths, transition probabilites, and charge transfer cross sections. In addition the subjects of ionization, photoionization, and excitation are discussed. The book also comprises a large number of figures and tables, with ample references. Simple analytical formulas allow one to estimate the atomic characteristics without resorting to a computer.