Quantum metrology leverages the unique properties of quantum mechanics to enhance measurement precision beyond classical limits. This paper provides a comprehensive review of the fundamental principles, resources, and techniques used in quantum metrology. We explore the role of quantum entanglement, squeezed states, and quantum correlations in improving measurement sensitivity. Various applications of quantum metrology, including quantum magnetometry, gravimetry, clocks, and interferometry, are discussed, highlighting recent advances and experimental implementations. We address the sources of errors in quantum measurements and outline strategies for error reduction and precision enhancement, such as quantum error correction. Emerging trends and future directions in the field are examined, along with potential industrial applications and the challenges that must be overcome. The outlook for quantum metrology is promising, with significant advancements expected to drive innovation across multiple scientific and technological domains.

Quantum metrology, quantum mechanics, measurement precision, quantum entanglement, squeezed states, quantum correlations, quantum sensing, quantum magnetometry, quantum gravimetry, optical lattice clocks, quantum interferometry, error correction, quantum noise, experimental setups, future trends.