What is GIS?
GIS is a computer-based, analytical tool that assembles, stores, manipulates, and displays
geographically referenced information. This system is composed of hardware, software and data. The
operating personnel, or GIS staff, are also considered a part of the GIS system. GIS technology is
used for scientific investigations, resource management, testing hypothesis, map distributions and
developmental planning.
A feature of GIS that separates itself from CAD and other graphical computer applications is that it is able to geographically reference spatial data (any information that has a spatial component, i.e. a location) to a map projection of an earth coordinate system. This information may vary from the
address of a customer to the average yearly rainfall distribution of a watershed. With GIS, spatial data
from different sources can be “re-projected” to a common mapping projection system.
This geographic transformation allows for the integration of large amounts of information and
applications that have a geographic component into one manageable system. Geographic information
from various databases can thus be brought together, organized, managed and distributed efficiently.
Another feature of GIS is “topology” which defines spatial relationships between features. The
fundamental components of spatial data are points, arcs (lines), polygons and points.
