.BIL File Extension

GIS file created in ESRI's BIL (binary interleaved) format, a raster image format used for representing surfaces and terrain elevations; can be georeferenced by another file to map the image data to the real world location.

BIL files can save satellite images or constructed elevation and surface data.

NOTE: BIL files are often accompanied by a .HDR file which describes the layout and formatting of the raster data.