A GIS consists of a database, map information, and a computer-based link between them. It is in essence a computer-based tool for mapping and analyzing places and events that have this geographic/spatial component. Since an overwhelming majority of data used in everyday work has a geographic/spatial component (i.e. an address, or a latitude/longitude coordinate), almost all human activity and natural phenomena can be studied using a GIS.

GIS technology integrates common database operations such as query and statistical analysis with the visual and geographic benefits offered by maps. These abilities distinguish GIS from other information systems and graphics software. The analytical component of GIS makes it a valuable tool in public and private enterprises for planning strategies, explaining events, and modeling future events.

A GIS can be used for diverse tasks such as SITE ANALYSIS (finding an ideal location for senior housing); ROUTING ANALYSIS (finding fastest routes to/from emergencies); TRANSPORTATION ANALYSIS (analyzing how traffic may be affected by new business or construction; determining which major employers are located within walking distance of public transportation); PROXIMITY ANALYSIS (how many, and which homes fall within 100 yards of a recently contaminated well); OVERLAY ANALYSIS (integrate different data layers for analytical purposes, i.e. analyze socioeconomic factors against outbreaks of disease); and finally, VISUALIZATION OF DATA (results of data analysis can be printed as maps, charts, or reports)

GIS is comprised of five key elements: hardware, software, data, people and methods.

Hardware is the computer on which a GIS operates. Peripheral equipment such as plotters, printers, scanners and digitizers are often a large component of the GIS.

GIS software provides the functions and tools needed to create, manipulate, analyze, manage, display and output geographic data.

Data is the key component of a GIS. Data can be collected and created in-house, or purchased from a commercial data provider. Some examples of data are: Roads, Parcels, Municipal Boundaries, School Districts, Census Tracts, Parks, Water Bodies, Landmarks, Historic Places, Bus Routes, Rail Lines, Major Employers, Schools, Wetlands, Demographics, Incidences of Disease/Illness, Traffic Counts, Libraries, Watersheds, Hazardous Material Locations, Geologic data, etc.

People manage the system and develop plans to apply it to real world problems. GIS users range from technical specialists who design and maintain the system, to those who use it to help them perform their everyday work.

A successful GIS needs well-designed methods to function efficiently. (whether it be collecting and maintaining data on a timely basis, or automating analysis done on a regular basis).

In 1993, the Rockland County Planning Department became increasingly aware of the advantages of thinking and working geographically and embraced this new technology. It has made mapmaking and geographic analysis much more efficient and has created new opportunities and resources for all County Departments.