GIS stands for Geographic Information Systems. A GIS is mapping software that links information about where things are with information about what things are like.

A GIS map can combine many layers of information. This information comes from a database. The database stores where a tree is located, how long a road is, and even how many square miles a lake occupies. Each piece of information in the map sits on a layer, and the user turns on or off the layers according to his needs. One layer could be made up of all the roads in an area. Another could represent all the lakes in the same area. Yet another could represent all the trees.

Why is this layering so important? The power of a GIS over paper maps is your ability to select the information you need to see according to what goal you are trying to achieve. Not only can you select what layers to view, you can also select (or query) specific information from each layer. These maps can then be viewed on a computer screen or printed on paper.