A world without this is almost unimaginable. This plays an essential role in various scientific fields and in industry. It is used throughout the home, at work, and often in play. One of the greatest benefits of this is that it lets in light and provides protection from the weather at the same time. This allows daylight in but keeps 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. Bottles can reveal their contents without being opened.