The role of APIs in mobile applications is to facilitate communication and data exchange between the app and external services or platforms. APIs enable mobile apps to access functionalities and data from other software components, leveraging resources without needing to recreate them from scratch. For instance, a weather app might use an API to fetch real-time data from a weather service. APIs enhance app capabilities by integrating third-party features, such as payment processing or social media sharing, ultimately enriching the user experience and allowing developers to build more complex applications efficiently.