The tfw world file is a text file used to georeference the geotiff raster images, like the orthomosaic and the DSM.
The tfw file is a 6-line file:
Line 1: pixel size in the x-direction in map units (GSD).
Line 2: rotation about y-axis.
Line 3: rotation about x-axis.
Line 4: pixel size in the y-direction in map in map units (GSD).
Line 5: x-coordinate of the upper left corner of the image.
Line 6: y-coordinate of the upper left corner of the image.
As pixels are considered as square lines 1 and 4 are the same.