Jack Dangermond, president of ESRI (www.esri.com), predicts that Web map services will become a kind of nervous system for the Earth, enabling GIS users to leverage geographic information to provide a framework for managing our planet's limited resources (see One Last Thing, Geospatial Solutions, July, 2002). Once you understand how these services really work, you may very well agree with him. And widespread agreement about Web map services is exactly what's required to fulfill Dangermond s prophecy. A true planetary nervous system needs millions of data feeds, small and large, all compliant with the same communication standard.

Eager to participate, but unnerved by the details? This article dissects exemplary Web mapping server URLs in an attempt to reveal their inner workings. Scrub up before we operate!