Imagine a tree. How would you keep track of and communicate information about this tree to other people who need to know all about it? You might use a database to keep track of what species it is, how old it is, how tall it is, how healthy it is, and any other attributes that are important. This tree is one record in a database. We call each category (i.e. tree height) a field.

Now imagine a grove of trees that you need to keep track of attributes for. Because we are now dealing with more than one tree, it becomes relevant where each tree is so we know what information relates to which tree.

We map the location of each tree and identify which attributes belong to which tree. This is the foundation of GIS. A GIS tells us where something is and what it is. Computers are synonymous with GIS, and using a computer we can have hundreds of fields (different attributes) for millions of records (trees).

You will be able to examine the attributes of features as you navigate Geographic Data Viewer maps.

We can also have other layers of information in our GIS. Our information on trees would constitute one layer of information. We could also have a layer with rivers and a layer with soil types. Any information can be represented as a layer.

A map represents the landscape in an artificial way. Vector layers represent features in one of several ways:

Points:A point is good for representing information in which it is necessary to show where a feature is, but its physical shape is not important (i.e. trees in the old growth tree layer).

Lines: A line is suitable to represent many real world features (i.e. the rivers in the river layer).

Polygons: Don't be intimidated by the name. It is really just a solid multi-sided shape. When you see a polygon, remember that everything inside the boundary has the attributes associated with the record. (i.e. soil types in the the soils layer)

You might hear people talk about coverages, themes, or shapefiles. All these terms are other names for layers of information.

With individual layers we can conduct analysis between layers and only display layers of interest.

As you are work with Geographic Data Viewer maps you will be able to turn different layers on and off as you desire.