The program is designed to find the names of all the routers through which an IP packet passes on the way from your Macintosh to the destination host. It can display these paths in tree form, or on a map of the world. In addition it measures the round-trip time from your Macintosh to the router thus enabling you to determine slow links (hops) in the Internet. It can also find dead links - ie routers that don't respond etc.