REST API integration involves connecting different software systems, allowing them to communicate and share data seamlessly. This process enables applications to leverage functionalities or retrieve information from external services by making HTTP requests. Through standardized endpoints, data is exchanged in a structured format, commonly JSON. RESTful principles, such as statelessness and uniform resource identifiers (URIs), guide this integration. Robust documentation, including API endpoints, methods, and authentication details, is essential for smooth implementation, ensuring effective communication between diverse systems and enhancing overall system interoperability.