A commonly used programming framework for building mobile applications is React Native. Developed by Facebook, this open-source framework allows developers to create high-quality mobile apps using JavaScript and React. React Native enables cross-platform app development for both iOS and Android, meaning developers can write code once and deploy it across multiple platforms. This approach reduces development time and costs while maintaining a native look and feel. With a rich ecosystem and community support, React Native has become a popular choice for modern app development.