The shapefile, or ESRI Shapefile, is an old and popular file format that's supported by most desktop GIS systems, but is rarely used directly in web maps. Shapefiles can be a moderately efficient way to transfer larger amounts of spatial data, but they have quirks and limitations that you should be wary of:
Placemark supports shapefiles as a .zip file containing .shp, .dbf, and .prj, or as those files dropped or selected into the map in one operation.
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