ESRI Shapefiles are not just the SHP file. While some importers can import the geometry from just that one file, a lot remains missing.  That’s why it’s important to send the package, not just a single SHP file.

Here is an overview of the primary files that make up the Shapefile collection.  They are listed in order of importance (at least as per this author).

Extension Description Importance
SHP Geometry definitions (coordinates, etc). Critical
DBF Database attributes for each shape object. Very
PRJ Projection information, describes where the file exists. Moderate
SHX Index telling the byte position of each object in the SHP. Minimal

Additional Notes:

  • The DBF file is simply a dBase database file.  As such it can be imported in other databases by itself, or can be opened in Excel (even older versions).  Be careful not to save over top the original as you could corrupt the Shapefile package.
  • Shapefiles cannot contain a mixture of objects.  In other words it’s all point, polylines, or some other class.  So don’t be surprised if there is more than one package in the collection.
  • Shapefile file names should be limited to 8.3 filenames during creation as per the ESRI specification (they wrote the book).  So if you’re one of those people who bloviate file names, consider that the files you create may be considered invalid in some shape file readers!  So keep it to eight (8) characters, no special characters or spaces (use an underscore if necessary).

The best way to provide the package to others is to zip up all the files.  That makes for a complete package, and it compresses the contents as well.  If you want more details on the Shapefile, follow up on the Wikipedia page.

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