<p>This paper reviews the evolving research fundamentals and emerging trends in sensor network metrology (SNM). SNM represents a transformative shift in measurement science by integrating traditional metrological principles with advanced digital technology. It has become necessary to make significant advancements in this field to achieve auditable, i.e., reliable and traceable, sensor networks. We emphasize the incorporation of machine learning, semantic technologies, and digital calibration certificates. It will ensure uncertainty management, traceability to SI units, and data quality, as sensor networks have rapidly spread across various fields. We discuss key applications and highlight the critical role of conforming metrological frameworks in addressing challenges. Also, we examine emerging trends with novel applications. Finally, a comprehensive roadmap toward auditable and sustainable sensor networks is outlined.</p>