NativeScript is an open source framework that allows developers to use web development skills like JavaScript, TypeScript, and Angular to build fully native mobile applications for iOS and Android. Unlike frameworks like PhoneGap, Ionic, Xamarin, and React Native, NativeScript provides direct access to native mobile APIs and components, allowing developers to build truly native user interfaces and experiences without compromising on performance. NativeScript supports building apps natively for iOS and Android in JavaScript or TypeScript and offers features like cross-platform code sharing, native UI layouts, plugins, and access to native APIs and components.