That's called a resource fork: https://en.wikipedia.org/wiki/Resource_fork https://en.wikipedia.org/wiki/Resource_fork Those files contain out-of-band metadata

That's called a resource fork: https://en.wikipedia.org/wiki/Resource_fork https://en.wikipedia.org/wiki/Resource_fork Those files contain out-of-band metadata for the given file. Now, for file systems that don't natively support resource forks (read: anything but Apple's own filesystem(s)), Finder insists on storing them as dot-underscore files. E.g. Mac clients are notorious for littering SMB shares with these dot-underscore files. As for why it's created when sharing stuff through AirDrop, from one Apple device to another, that's beyond me... I think it might make sense to hide these dot-underscore files from the file browser, along with .DS_Store and maybe thumbs.db (I'm not even sure whether modern Windows still creates thumbs.db). Will do it in the next version. Thanks for the feedback! I wanted exactly this iOS-native look & feel you're talking about. I personally don't like other apps forcing their designers' UX vision on me... A curated music library with quality artworks speaks for itself. I don't want my app to stand between users and their libraries :)