A. It's a graph of how the Internet might look if you were a packet of data like an e-mail message. The lines show the paths you might take, network-by-network, if you started at a computer in the U.S. and visited almost every known network around the world. The lines branch at each network switch or router along the way.

Q. How was the graph created?

A. The latest graph was made by recording the shortest path taken by test messages sent on January 1, 2002, from a computer in Somerset, New Jersey, to each of the 177,017 odd networks registered in the routing databases kept by Merit Network Inc and other authoritative sources. The data were then graphed using special software developed by Hal Burch, while a PhD student at Carnegie Mellon University, and Bill Cheswick, while a scientist with an affiliate of Lucent Technologies. Their research into large-scale network mapping is now being applied commercially by Lumeta Corporation.

Q. What do the colors mean?

A. The colors highlight the geographical and commercial distribution of the Internet's various networks. Colors were assigned based upon the top level geographic domain (for example, .de for Germany) or industry category (.net for Internet service provider) where each network router was registered. (Caution: Even though a router is registered in a particular country, it may not be located there.)