The term native app is used to refer to platforms such as Mac and PC, with examples such as the Photos, Mail or Contacts applications that are preinstalled and configured on every Apple computer. However, in the context of mobile web apps, the term native app is used to mean any application written to work on a specific device platform.
The two main mobile OS platforms are Apple's iOS and Google's Android. Native apps are written in the code preliminarily used for the device and its OS. For example, developers write iOS applications in Objective-C or Swift, while they create Android-native apps in Java.