GIS - Geographic information system. An organized collection of computer hardware, software, geographic data, and personnel designed to efficiently capture, store, update, manipulate, analyze, and display all forms of geographically referenced information.

Coverage/Layer - 1. A digital version of a map forming the basic unit of vector data storage in ARC/INFO. A coverage stores geographic features as primary features (such as arcs, nodes, polygons, and label points) and secondary features (such as tics, map extent, links, and annotation). Associated feature attribute tables describe and store attributes of the geographic features. 2. A set of thematically associated data considered as a unit. A coverage usually represents a single theme such as soils, streams, roads, or land use.  In MapInfo a "coverage" is referred to as a Layer(s).

TIGER - Topologically Integrated Geographic Encoding and Referencing data format used by the U.S. Census Bureau to support census programs and surveys. It was used for the 1990 census. TIGER files contain street address ranges along lines and census tract/block boundaries. This descriptive data can be used to associate address information and census/demographic data with coverage features.

Point -  A single x,y coordinate that represents a geographic feature too small to be displayed as a line or area; for example, the location of a mountain peak or a building location on a small-scale map.

Line - 1. A set of ordered coordinates that represents the shape of geographic features too narrow to be displayed as an area at the given scale (e.g., contours, street centerlines, or streams), or linear features with no area (e.g., state and county boundary lines).  2. A single arc in a coverage. 3. A line on a map (e.g., a neatline). FYI - arc is an ordered string of vertices (x,y coordinate pairs) that begin at one location and end at another. Connecting the arc's vertices creates a line. The vertices at each endpoint of an arc are called nodes.

Polygon- A coverage feature class used to represent areas. A polygon is defined by the arcs that make up its boundary and centroid inside its boundary for identification. Like Points, and Lines, Polygons have attributes that describe the geographic feature they represent.

Thematic Mapping - the process by which attribute data is presented or described on a map using ranges, pie charts, bar charts, graduated symbols, dot density, titles, labels and legends.

Geocoding  - The process of identifying the coordinates of a location given its address or some other x,y coordinate (e.g. a centroid of a polygon). For example, an address can be matched against a TIGER street network to determine the location of a home.

Spatial Analysis - The process of modeling, examining, and interpreting model results. Spatial analysis is useful for evaluating suitability and capability, for estimating and predicting, and for interpreting and understanding.   The most common form of spatial analysis involves

Map Scale - The reduction needed to display a representation of the Earth's surface on a map. A statement of a measure on the map and the equivalent measure on the Earth's surface, often expressed as a representative fraction of distance, such as 1:24,000 (one unit of distance on the map represents 24,000 of the same units of distance on the Earth). Map scale can also be expressed as a statement of equivalence using different units; for example, 1 inch = 1 mile or 1 inch = 2,000 feet.

Map Projection - A mathematical model that transforms the locations of features on the Earth's surface to locations on a two-dimensional surface. Because the Earth is three-dimensional, some method must be used to depict a map in two dimensions. Some projections preserve shape; others preserve accuracy of area, distance, or direction.

Coordinate System - A reference system used to measure horizontal and vertical distances on a planimetric map. A coordinate system is usually defined by a map projection, a spheroid of reference, a datum, one or more standard parallels, a central meridian, and possible shifts in the x- and y-directions to locate x,y positions of point, line, and area features. A common coordinate system is used to spatially register geographic data for the same area.

Social Scientists - demographic analysis: siting of health clinic for low-income children (vs. elderly), survey research: business pattern corridor study.

Planners - comprehensive land-use: represent values of the community, farmland preservation, zoning: issuance of permits, variances, enforcement,  land evaluation site assessment: transportation: traffic signalization, snow and ice removal, bridge sufficiency ratings, etc.

Utility Providers - water: watershed analysis, wellhead protection, water distribution system; sewer: wastewater collection system, topography for gravity vs. lift-station; solid waste: landfill siting,  electric & gas: service grid for outage repair.

Public Safety - police: provide 911 service maps, crime analysis, fire and ems: analyze response times to locate a new station.

County Officials: Auditor: property tax assessment: automation allows frequent re-assessment, Engineer, Board of elections: electoral districts: charter commission consideration, Politicians/Policy-makers.