The paper by Koshchev et al. explores the high-Q resonances in metasurfaces composed of meta-atoms with broken in-plane symmetry, revealing a direct link between these resonances and bound states in the continuum (BICs). The authors demonstrate that various metasurfaces, including those with tilted bars, asymmetric holes, and plasmonic structures, can support sharp high-Q resonances. They rigorously prove the connection between BICs and Fano resonances, providing a general theory for engineering resonances in nanophotonics and meta-optics. The study introduces a novel analytical approach to describe light scattering by arrays of meta-atoms, showing that the Fano parameter becomes ill-defined at the BIC condition. The authors derive a universal formula for the Q factor as a function of the asymmetry parameter and demonstrate the quadratic scalability of the radiative Q factor. This work paves the way for smart engineering of photonic structures with tailored properties, such as nanolasers, light-emitting metasurfaces, and optical sensors.The paper by Koshchev et al. explores the high-Q resonances in metasurfaces composed of meta-atoms with broken in-plane symmetry, revealing a direct link between these resonances and bound states in the continuum (BICs). The authors demonstrate that various metasurfaces, including those with tilted bars, asymmetric holes, and plasmonic structures, can support sharp high-Q resonances. They rigorously prove the connection between BICs and Fano resonances, providing a general theory for engineering resonances in nanophotonics and meta-optics. The study introduces a novel analytical approach to describe light scattering by arrays of meta-atoms, showing that the Fano parameter becomes ill-defined at the BIC condition. The authors derive a universal formula for the Q factor as a function of the asymmetry parameter and demonstrate the quadratic scalability of the radiative Q factor. This work paves the way for smart engineering of photonic structures with tailored properties, such as nanolasers, light-emitting metasurfaces, and optical sensors.