Apps that are not preinstalled are usually available through application distribution platforms , which began appearing in 2008 and are typically operated by the owner of the mobile operating system , such as the Apple App Store , Google Play , Windows Phone Store , and BlackBerry App World .
These began appearing in 2008 . They are typically operated by the owner of the mobile operating system , such as the Apple App Store , Google Play , Windows Phone Store , and BlackBerry App World .