Coherent states in quantum optics

The first part of the paper summarizes the results of Roy J. Glauber on the coherent states that is the fundamentals of quantum optics. Then some non-classical states of light are shown like squeezes light, a state with smaller quantum noise than in coherent state. Later on photon number states and amplitude squeezed states have been described. The final part gives examples on applications of quantum optics like some laser applications, trapped ions and quantum informatics. (T-R.A.)