Explore the foundations of quantum metrology and its applications in precision measurements in this lecture by Fritz Riehle. Delve into the theory and practice of using quantum resources like entanglement, superposition, and coherence to achieve unprecedented accuracies in measurement. Learn about the latest developments in quantum-based SI standards and their importance in pushing the boundaries of scientific discovery. Gain insights into the fundamental principles of quantum physics that enable these advanced measurement techniques, and understand how they are revolutionizing fields from atomic clocks to gravitational wave detection. This lecture is part of a comprehensive program on Precision Measurements and Quantum Metrology, designed to build knowledge and awareness among future researchers in this cutting-edge field.