Traditional photo editing is ‘destructive’. That means every adjustment you make permanently changes the pixels in the photo and there’s no way back unless you’ve saved a copy of the original and you’re willing to start again. ‘Non-destructive’ editing is fully reversible. You can go back and undo or redo all of your editing work […]
These are small files containing processing information stored alongside image files. They're used by non-destructive photo editing and RAW processing programs to store editing adjustments as 'metadata' and should not be separated from the image file they below to, or these adjustments will be lost.