Reference

PKG (installer)

A PKG file is a macOS installer package. It bundles an app or system component plus scripts that copy files into place and configure them, so double-clicking runs a guided installer rather than just dragging an app to Applications.

Files & formatsmacOS

PKG (installer)

Also known as: PKG file, .pkg installer, macOS installer package

macOS installer package with scripts
Can place files system-wide and request admin rights
Only install PKGs from trusted sources

Installer, not just a copy

Many Mac apps install by dragging a .app into Applications. A .pkg is the alternative: a packaged installer that can place files in multiple locations, run pre- and post-install scripts, and require admin permission.

Software that needs system-level setup — drivers, command-line tools, system extensions — commonly ships as a PKG.

Working with PKG files

Double-click a PKG to launch the macOS Installer and follow the prompts. Only install PKGs from trusted sources, since they can run scripts with elevated privileges.

Tools like Pacifist or Suspicious Package can inspect a PKG to see exactly what it would install.

Related terms

Keep reading the reference.

Files & formatsDMG (Apple disk image)A DMG is Apple’s disk-image format, used mainly to distribute Mac apps. You double-click it to mount a virtual drive, drag the app to Applications, then eject and delete the .dmg — you do not "install" the DMG itself.macOSGeneral Files & formatsArchive fileAn archive file bundles many files and folders into one container — for example a ZIP, RAR, or 7z. Most archives also compress their contents to save space, but some (like plain TAR) only bundle without shrinking anything.General Files & formatsDisk imageA disk image is a single file that mirrors the entire contents of a disk or volume — its file system, structure, and data. Common types include ISO (discs), DMG (macOS), and IMG. You mount or write a disk image rather than just extracting files from it.General