The article provides an overview of optical magnetometry, a technique that uses interactions of resonant light with atomic vapor to measure magnetic fields. Recent advancements in this field have improved traditional applications such as geomagnetic anomaly detection and space magnetic field measurements, and opened new areas such as bio-magnetic field detection, nuclear magnetic resonance (NMR) detection, magnetic resonance imaging (MRI), inertial-rotation sensing, magnetic microscopy with cold atoms, and tests of fundamental symmetries of nature. The most sensitive atomic optical magnetometer, the spin-exchange-relaxation-free (SERF) magnetometer, has demonstrated a sensitivity exceeding \(10^{-15} \, \text{T} / \sqrt{\text{Hz}}\), with projected fundamental limits below \(10^{-17} \, \text{T} / \sqrt{\text{Hz}}\). The article discusses the basic principles, fundamental limits, and specific applications of optical atomic magnetometers, including their use in biological magnetic field detection, fundamental symmetry tests, and space magnetic field measurements. It also highlights the advantages of atomic magnetometers over SQUID-based magnetometers, such as the ability to operate at room temperature and the potential for miniaturization.The article provides an overview of optical magnetometry, a technique that uses interactions of resonant light with atomic vapor to measure magnetic fields. Recent advancements in this field have improved traditional applications such as geomagnetic anomaly detection and space magnetic field measurements, and opened new areas such as bio-magnetic field detection, nuclear magnetic resonance (NMR) detection, magnetic resonance imaging (MRI), inertial-rotation sensing, magnetic microscopy with cold atoms, and tests of fundamental symmetries of nature. The most sensitive atomic optical magnetometer, the spin-exchange-relaxation-free (SERF) magnetometer, has demonstrated a sensitivity exceeding \(10^{-15} \, \text{T} / \sqrt{\text{Hz}}\), with projected fundamental limits below \(10^{-17} \, \text{T} / \sqrt{\text{Hz}}\). The article discusses the basic principles, fundamental limits, and specific applications of optical atomic magnetometers, including their use in biological magnetic field detection, fundamental symmetry tests, and space magnetic field measurements. It also highlights the advantages of atomic magnetometers over SQUID-based magnetometers, such as the ability to operate at room temperature and the potential for miniaturization.