Cross-platform apps are software applications designed to work on multiple operating systems, such as iOS, Android, and Windows. This means that developers can create a single version of the app that runs seamlessly on different devices, saving time and resources. These apps are built using frameworks like React Native or Flutter, which allow for a shared codebase. This approach not only simplifies the development process but also ensures a consistent user experience across various platforms, making it easier for users to access the app regardless of their device choice.