.BIL File Extension
What is a BIL file?
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 an .HDR file, which describes the layout and formatting of the raster data.