"the need is mother inventions"
This saying is best definite evolution humanity and development of industry ( for instance energetistic). Electricity were know to human a long time ago. Associate of ligtning and electric charge, who spark and know draw some things. On everyday live we use facility, whos were long time ago.
Mobile phones is the most important invention.
The invention of the cellphone or mobile phone dates back to the year 1947. The cellphones was a two-way radio. the technology wasn't very developed and only twenty-three conversations were possible in one area. In 1968 there was already a system of towers, each was a "cell", and could broadcast waves for a few miles. When people carried a phone from place to place, telephone conversations passed from one tower to another. The first commercial cellular phone system started working in 1979 in Tokio. In 1982 the USA had a celluar system that everybody could use. More and more people started using cellphones and suddenly they were everywhere.