Caption

Visualisation of data traffic over a US national computer network. The computer image shows the volume of data travelling into the National Science Foundation Network (NSFNET) in one month (September 1991). The colours represent traffic volume from zero (purple) to 100 billion bytes (white). The 'backbone' of the system is the white network between main data centres (top). Each main centre serves numerous regional users (purple/ yellow lines). NSFNET enables any US scientist to access supercomputers from their own workstations.