The article provides an overview of recent advancements in quantum metrology, a field that leverages quantum effects to enhance measurement precision beyond classical limits. The authors discuss the central limit theorem in classical estimation theory, which suggests that statistical errors can be reduced by averaging multiple measurements, but quantum techniques, such as entanglement, can achieve even better results, reducing errors by a factor of $n^{-1}$. They analyze the theory and new experiments in quantum metrology, focusing on the optimization of probe readout and the analysis of noise and experimental imperfections. The paper also covers quantum estimation for states, operator-valued measurements, and the quantum Cramér-Rao bound, which sets the ultimate precision limits. Additionally, it explores quantum parameter estimation for channels and the application of quantum interferometry, including the Mach-Zehnder interferometer. The authors discuss the challenges and achievements in practical quantum metrology, such as the use of entangled states and filtering protocols, and the impact of noise on quantum metrology. They conclude by highlighting the potential of quantum metrology in various applications, despite the current limitations and the need for robust strategies to handle noise and decoherence.The article provides an overview of recent advancements in quantum metrology, a field that leverages quantum effects to enhance measurement precision beyond classical limits. The authors discuss the central limit theorem in classical estimation theory, which suggests that statistical errors can be reduced by averaging multiple measurements, but quantum techniques, such as entanglement, can achieve even better results, reducing errors by a factor of $n^{-1}$. They analyze the theory and new experiments in quantum metrology, focusing on the optimization of probe readout and the analysis of noise and experimental imperfections. The paper also covers quantum estimation for states, operator-valued measurements, and the quantum Cramér-Rao bound, which sets the ultimate precision limits. Additionally, it explores quantum parameter estimation for channels and the application of quantum interferometry, including the Mach-Zehnder interferometer. The authors discuss the challenges and achievements in practical quantum metrology, such as the use of entangled states and filtering protocols, and the impact of noise on quantum metrology. They conclude by highlighting the potential of quantum metrology in various applications, despite the current limitations and the need for robust strategies to handle noise and decoherence.