The communications world is changing, and packet-switched networks are taking over. Traditionally, telephone networks have relied on a circuit-switched architecture-that is, when one user makes a call to another, a circuit within the network is opened and dedicated to that call for as long as the call lasts. In the 1960s, however, scientists began developing packet-switching techniques for communicating information. In packet-switching, the information (a telephone conversation, video clip, computer program, newspaper article, or something else) is sliced up into small packets, each carrying its own copy of the destination address. The packets travel individually to their destination, not necessarily over the same route, and are reassem...