Sometimes you need aggregated information across a surface. This could be population density per square mile or grasshopper infestations per square kilometer. Density grids can be used as weights for modeling such as business models or pesticide models, to best make use of your limited resources. Once you have either opened or generated a grid you can explore the data in a more conventional manner using the contour functionality. You can generate contours by interactively picking locations on the screen or by generating a set of contours at a specified interval.
Contours are useful in showing topographic relief across a surface.
However, sometimes you need more detailed information about a grid such as the topographic attributes. Topographic attributes are often very important to agriculture and natural resource applications. Many natural and human processes are dependent on functions of these variables such as slope, aspect, curvature, and stream flow. You can use both attributes and location to solve your problems with the Spatial Analyst. One application of this is to use the distance and proximity functions to ask questions concerning how far something is and to generate allocated areas.