A folder with a .TRASHES extension is a folder created by macOS to store files that are marked for deletion but have not yet been deleted. It is created and placed on a USB flash drive that has been connected to a computer running macOS. TRASHES files can be deleted to free up space on the USB flash drives they are located on.

Most users will not come across a TRASHES file since it is hidden and only appears on USB flash drives that have been connected to a computer running macOS. The TRASHES file is technically a folder and is created on a USB flash drive when a user moves files from the flash drive to the trash in macOS but has not yet emptied the trash, which permanently deletes the files. Although the TRASHES file is typically seen in File Explorer when the USB flash drive that was connected to the computer running macOS is connected to Windows. A user can simply double-click the TRASHES file to open it in File Explorer the same way he would open a folder. He can then retrieve any files that were not yet permanently deleted when the USB flash drive was connected to the computer running macOS. If a user needs to free up space on his USB flash drive, he can delete the TRASHES file or simply empty the trash bin in macOS where the files in the TRASHES file have been moved to.