The CO2-laser technology may be considered the most advanced in the laser field. Research has been stimulated strongly because of its high potential for many scientific and industrial applications. This book is primarily devoted to the main, more established developments of the CO2-laser. Advances in continuous systems, pulsed systems, mode-locked pulses, and the amplification of short pulses are dealt with in detail. This is done by giving an extensive treatment of relevant molecular physics, gas kinetics, excitation and relaxation processes, and laser physics pertinent to CO2. It also provides a thorough theoretical background of specific technologies used in various devices. Many numerical values of physical constants and accurate spectroscopic data of CO2 isotopes are included.