PKG, Mac OS X Installer Package (.pkg)
The PKG Settings file format
PKG files can be found on Apple computers running under Mac OS X. These files contain a package of compressed files used for the installation of different software on a Mac. Software contained in a PKG file can be installed by simply double-clicking on the PKG. To view the individual contents, a right-click is needed.
Technical details of PKG files
PKG files are typically used to install software and programs on a computer running with Mac OS X. The programs can be installed individually by manually double-clicking and thus executing the PKG files. However, PKG files can also be part of an installer script that executes the PKG files automatically when run.