When you open your folder you may see duplicate files which start with ._

._ files are created automatically by Mac OS X and contain metadata related to the accompanying file that was placed there by programs in the Mac. ( All my work is created on a Mac, so this will happen if you open them on PC. ) These are invisible files.

Deleting these files is not advised because they contain information that could not be supported by the file format that is presented as for your computer. This information is referenced by programs when their associated files are opened on the Mac OS.

Macs will split extra information for files into these ._ files (since the drive type being used in these cases is not Mac-specific).

.DS_Store Files Beyond the creation of resource fork files, OS X is notorious for cluttering windows-formatted volumes with other hidden files, such as trash folders and the irritating ".DS_Store" files which hold folder-specific settings.

These files can be created even when users just browse a windows volume, and while they may be invisible to Macintosh users, Windows users will see them created all over the place. Fortunately, deleting these files manually will not harm anything, but it can be very annoying to users to have these files constantly appearing.

There are several ways to manage these hidden files, and prevent them from occurring.