The knowledge-based economy is a network economy. The part that networks play in society is not a new thing, but perhaps their application and study are. The survival of the Roman Empire was undoubtedly due to its network of roads and the ease with which its culture, troops and merchandise could move about through its territories. The industrial revolution of the 19th century, and the fact that it extended to all four corners of the world, was thanks to the railway network which aided the spread of technology at levels never before seen. The second great industrial revolution – that of the electric engine – was also accompanied by the appearance and growth of electricity distribution networks and an improvement in communications and transport.