I get frustrated when people hear "GIS" (geographic information systems) and immediately think "oh, it's a map." Well, yes, it is a map--in the same way that a database is "just a spreadsheet." More importantly, it's a way of interpreting and relating data.

As we, as a society, begin to aggregate more and more data, we're faced with the challenge of using that data in a meaningful way. The task is even more difficult when some of your datasets are incomplete. Let's think about it with the following example--a great use of GIS by the UN.

The most important sentence in that article is that the system "allows users to overlay maps from multiple servers housed at development institutions worldwide to create a customized thematic composite map on their own computer." In one institute, they might have soil quality information for major metropolitan areas. In another, they have the latest population statistics for the entire country. Or perhaps a file that has the address of every power plant. Say you're in charge of reconstruction in a given suburb. Without the map, how would you be able to visualize this information? One person sends you a spreadsheet with soil quality, soted by city. Another one sends you the population statistics, and then you receive a Word document with the addresses. How do you make sense of all this without a single axis that brings them all together?

The visual manifestation of the map--the physical north-south-roads-mountains-cities picture--is not always necessary for interpreation. Imagine that what you really needed to know is whether any power plants were located in sparsely populated areas. You don't even have to look at a map to find this information--the map is just a way of relating the data. The machine can read the map and spit your answer back out at you without you ever seeing a compass rose.

And the most fun part is that once you have the basic layers, finding new data sets is great fun. Plug in the free database of US colleges, and you can target colleges located along rivers to find volunteers for Clean Water Action. Add in state legislative boundaries, and start them writing to their state reps. Yes, it's a map. But it's more than this--it's a way of gathering facts and putting them in a context where they're allowed to signify.