JSON (JavaScript Object Notation) is the best format for a penetration tester to use when they need the output of a reconnaissance script in a standardized machine-readable format to pass data to another application. JSON is widely supported across different programming languages and platforms, making it an ideal choice for data interchange. It allows for the hierarchical organization of data, is easy to read and write, and can be parsed and generated by numerous tools and libraries. This makes JSON a versatile and practical choice for a variety of applications in penetration testing and beyond. References: * RFC 8259 - The JavaScript Object Notation (JSON) Data Interchange Format * OWASP - JSON Security