Edison made the first public demonstration of his incandescent light bulb on December 31, 1879 in Menlo Park. It was during this time that he said, "We will make electricity so cheap that only the rich will burn candles." Now, many citizens can afford to use a light bulb at night and can enjoy any kind of night entertainment thanks to the light bulb. Nowadays, there are more than 500 billion electric lights in the world that decorate the Earth at night. The number of lights at night is a standard for measuring whether a country is developed or not. For example, in South Korea the light covers almost the entire country, while in North Korea there are some in the capital. The Internet is another practical use of electricity as users have to use electronic devices to browse the Internet. Internet connects the world together, sends the message in seconds. In the past, traveling and meeting was difficult and people wrote letters and books to exchange ideas and thoughts. Using the Internet, people can use email, blogs, Twitter, Facebook and can use the +visible system to communicate "face to face" with people miles away through the Internet without moving away