Installer is an application included in OS X (and in its progenitors OPENSTEP and NeXTSTEP) that extracts and installs files out of .pkg packages. It was created by NeXT, and is now maintained by Apple Inc. Its purpose is to help software developers create uniform software installers.Installer resides at /Applications/Utilities/Installer.app on Macintosh computers running OS X versions prior to 10.5, and launches when a package or metapackage file is opened.