You can hardly imagine a world without glass. Glass plays an indispensable role in ___VARIOUS___ scientific fields, in industry, and in telecommunications. It is used throughout the home, at work, and often in play. For centuries, glasswork has been a ___DECORATIVE___ form of art. One of the greatest benefits of glass is that it lets in light and provides ___PROTECTION___ from the weather at the same time. Glass windowpanes admit daylight but keep out cold or ___STORMY___ weather. Electric bulbs transmit light but keep out the oxygen that would cause their hot filaments to burn up. Television picture tubes enable ___VIEWERS___ to see the image that is formed inside the tube. Glass jars and bottles can reveal their contents without being opened. The principal reasons for the widespread use of glass are that most glass products can be made ___CHEAPLY___ and many kinds of glass can be made to suit particular purposes.