APIs, or Application Programming Interfaces, play a crucial role in connecting different software applications. They enable various systems to communicate and exchange data seamlessly by defining protocols and tools for building software components. APIs allow developers to access specific features or data from other applications without needing to understand their internal workings, thus promoting interoperability. This facilitates the integration of disparate systems, enhances functionality, and enables innovation by allowing third-party developers to create new applications or leverage existing services. Overall, APIs are essential for building connected ecosystems in modern software development.