XPlat Windows APIs are designed to make it easier for Universal Windows Platform (UWP) developers to share their knowledge of the platform APIs across Android and iOS.
XPlat also appeals to developers looking to migrate their existing code bases to Xamarin with minimal code change by mimicking Windows APIs allowing an easy transition to the equivalent XPlat API.
For example, if your application takes advantage of the Windows.Storage (e.g. Windows.Storage.ApplicationData.Current.LocalFolder), we provide a XPlat.Storage API for those (e.g. XPlat.Storage.ApplicationData.Current.LocalFolder) which you can use in your iOS and Android applications.