The Nets were an Internet-like network of connections between computers. It required a Citizen Access to be used by the average person.
Valentine and Peter Wiggin accessed The Nets under the pseudonyms of Demosthenes and Locke, respectively. They visited various political forums, and later wrote columns on The Nets.
It is interesting to note that the World Wide Web, the modern form of the Internet, was not invented until 1990, 5 years after Ender's Game was published. Orson Scott Card accurately predicted how much influence the nets would have, years before they became a daily part of people's lives.