This book provides fundamentals to glassy state and glass transition and criteria for glass formation. Important structural models such as Continuous Random Network (CRN) model and Random Close Packing (RCP) model have been discussed. It provide introduction to the oxide glasses such as Borates, Phosphates, Vanadates, Silicates and Germanates. It also discusses important properties of Ion conductivity, Mechanical, Spectroscopic and Optical properties.