Decision making support
In your daily business you make many decisions mostly based on the reports you get from your own dadabase but also you may use external statistical datas. GIS helps you to bring both together and related them to there concret locations so you can base your decisions on a spatial relevance datas provide.
To see your datas on a map overlayed it needs only seconds for getting a clear picture of the situation and makes you able to value the relation between different locations in the right way.