Tuesday Term of the Week | Shapefile

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A shapefile is a standard GIS data format for representing geographic features in a set of computer files.  Shapefile format can includes points, lines or polygons as vectors, along with associated attribute data. For example, a polygon might represent the region of a neighborhood and an associated attribute value could be the name of the neighborhood. Shapefile format was introduced in the early ‘90s by ESRI and its definition is publicly available.  A strength of the format is found in its relative simplicity. Each shapefile may only contain one type of vector geometry. Since shapefiles files lack a topographical data structure, they deliver faster drawing and edit capabilities and also require less digital storage space than more complex formats.

The actual shapefile file extension (.shp) must be used with the support of at least two additional files.  An .shx file adds a positional geometry index for faster access and map drawing. The .dbf file, based on dBASE database format, is used to store the attributes. By creating large data files containing numerous data points, lines or polygons along with associated  attributes, extensive maps can be created.

Shapefiles can be read, edited and their maps drawn using many standard GIS software packages.