API-based backend development refers to the construction of a server-side infrastructure that primarily relies on Application Programming Interfaces (APIs) to enable communication and data exchange between the server and various client applications, such as web or mobile apps. This approach modularizes the backend, allowing for a more scalable and flexible architecture. API-based development facilitates seamless integration with third-party services and ensures a decoupled system where different components can communicate efficiently. By adopting this methodology, developers can enhance interoperability, streamline development processes, and enable the creation of robust, interconnected ecosystems in web and mobile applications.