Files with a PKG file extension are mostly linked to the Apple OS X operating system. This is the platform where most users can commonly see PKG files in use. This is due to the fact the PKG files are installer or script files that are used by numerous Mac applications for installation in a Mac operating system. PKG stands for “package” as it is a package of compressed installer files that is used to either install or update an installation of a Mac application. This file format or extension was developed for the purpose of uniformity, seamless and easy installation and updates of programs and/or applications.
Files with a PKG file extension are executable files. It can be used directly for installing a program or can be referenced by an installer script that is included in the software installer. To open a PKG file therefore, a user just needs to double-click it to show the contents of the package. Opening the PKG file will automatically extract its contents and execute the installation script in the installer file.
PKG files are highly customizable. Programmers can opt to have the installer display a welcome message prior to installation, present software license information and manipulate “Read Me” file or data. PKG files can also be made to verify whether the files itself are still valid or authenticated. PKG files may also contain several scripts that could be running simultaneously depending on the needs of the software to be installed. PKG files of this nature however are proprietary of Apple or Mac operating systems and thus it can only be opened using an Apple Installer.