The blog of the Library of Congress’s Geography and Maps Division isn’t the first place you’d expect an explanation of the GeoTIFF format (basically, an image file in TIFF format that includes georeferencing metadata, so that the image can be projected on a map grid). But georeferencing old maps so that they can be placed on a modern map grid is definitely a thing, and Carissa Pastuch’s piece, “The Secret Life of GeoTIFFs,” looks at GeoTIFFs through the lens of an experimental dataset of georeferenced late 19th- and early 20th-century Austro-Hungarian maps.