For other uses see PKG.

.pkg is a file format used by Apple Inc. on its Macintosh

Macintosh

The Macintosh , or Mac, is a series of several lines of personal computers designed, developed, and marketed by Apple Inc. The first Macintosh was introduced by Apple's then-chairman Steve Jobs on January 24, 1984; it was the first commercially successful personal computer to feature a mouse and a...

 line of computers, and the iPhone

IPhone

The iPhone is a line of Internet and multimedia-enabled smartphones marketed by Apple Inc. The first iPhone was unveiled by Steve Jobs, then CEO of Apple, on January 9, 2007, and released on June 29, 2007...

. It's also used by Sony

Sony

, commonly referred to as Sony, is a Japanese multinational conglomerate corporation headquartered in Minato, Tokyo, Japan and the world's fifth largest media conglomerate measured by revenues....

's PlayStation 3

PlayStation 3

The is the third home video game console produced by Sony Computer Entertainment and the successor to the PlayStation 2 as part of the PlayStation series. The PlayStation 3 competes with Microsoft's Xbox 360 and Nintendo's Wii as part of the seventh generation of video game consoles...

 on downloadable content over PlayStation Network.

.pkg files are built on the xar

Xar (archiver)

Xar is an open source file archiver and the archiver’s file format. It was created within the OpenDarwin project and is used in Mac OS X 10.5 for software installation routines, as well as browser extensions in Safari 5.0...

 format. The contents of a .pkg file can be installed by Apple's Installer

Installer (Mac OS X)

Installer is an application included in Mac OS X which extracts and installs files out of .pkg packages. It was created by NeXT, and is now maintained by Apple Inc...

 application. The .pkg file format allows easy installation of software by end users, and is commonly used by both Apple and third-party developers.

.pkg files are also used as instruction sets to compile Symbian

Symbian

Symbian is a mobile operating system and computing platform designed for smartphones and currently maintained by Accenture. The Symbian platform is the successor to Symbian OS and Nokia Series 60; unlike Symbian OS, which needed an additional user interface system, Symbian includes a user...

 .sis installer files and contain data such as the vendor name, software dependencies, and application files that must be copied.

In the 90's, the .pkg file suffix was also used in BeOS

BeOS

BeOS is an operating system for personal computers which began development by Be Inc. in 1991. It was first written to run on BeBox hardware. BeOS was optimized for digital media work and was written to take advantage of modern hardware facilities such as symmetric multiprocessing by utilizing...

. Be bought a company called StarCode and acquired their packaging tools.

During the 90's, Apple's Newton

Newton (platform)

The Newton platform was an early personal digital assistant and the first tablet platform developed by Apple, the second platform being iOS, used in the iPhone, iPod Touch and iPad. Development of the Newton platform started in 1987 and officially ended on February 27, 1998. Some electronic...

operating system also used files ending in .pkg for Newton applications and software. As a result, when seen from a Mac OS X computer, Newton applications appear the same as Mac OS X Installer packages, however they do not share their file format.