GIS Basics




Definition of a GIS:


A Geographic Information System is a system of computer software, hardware and data, and the personnel that makes it possible to enter, manipulate, analyze, and present information that is tied to a location on the earth’s surface.



Components of a GIS are the combination of:




                                          +                                             +




Computer Hardware

and Software


Spatial Data from

the “Real World”


Trained Personnel








Hardware is the computer on which GIS operates.  The software runs on a wide range of hardware types, from centralized computer servers to desktop computers used in stand-alone or networked configurations.


GIS software provides functions and tools needed to input and store geographic information.  It also provides query tools, performs analysis, and displays geographic information in the form of maps or reports. 


All GIS software packages rely on an underlying database management system (DBMS) for storage and management of the geographic and attribute data.  The GIS communicates with the DBMS to perform queries specified by the user.




Data is one of the most important and expensive components of a GIS.  Geographic data and related tabular data can be collected, purchased from a commercial data provider, or downloaded for free from a number of sources.  PASDA, which is the official spatial data clearinghouse of Pennsylvania, provides GIS data free of charge.


There are two types of data used in GIS:



We will explain these in further detail later in the basics.


Trained Personnel


The people who are trained to manage the system and develop plans for applying real-world problems are what make a GIS so powerful.  There is a wide range of users from a technician an analyst who use GIS to for their everyday work, or a specialist who may design and maintain a system.