What is GIS?
The definition of GIS may change according to the application of a particular user. In general, a GIS is a computer software package designed for capturing, storing, analyzing, manipulating, integrating, and displaying data that are spatially referenced in some way -- traditionally to the earths surface (some GIS applications can involve spatial referencing that has nothing to do with the earth). A GIS should be able to provide these functions:
2. The ability to select objects by area or theme (e.g. select all streets within 10 kilometres of my address)
3. Link or merge data sets
4. The ability to analyze spatial characteristics (e.g. area, length, perimeter)
5. Search and query
6. Modeling
7. Statistical analysis
8. Hard copy map layouts
It is best to think of a GIS and the spatial data sets within as a representation of the real world. Traditionally, paper maps were used to graphically represent features on the earth's surface. Maps often show roads, rivers, urban areas, forested areas, elevation information, and water bodies. These different features are essentially different types of data, or themes. In a GIS, these different themes are separated into layers. Each of these layers may be used individually, or overlaid one on top of the other. The attribute information in each of the layers (i.e. street names, speed limits, addresses, river names, etc) are stored in a database in a series of tables within the GIS.
The maps can be viewed and queried for specific information. For example, one can find and display all the schools within five kilometres of an address, or find the closest hospital. The different types of uses for a GIS are endless, and are limited only by the type and quality of the information and data sets available.